Here is a rough estimation of the RHAE values for most tanks. Please note that this is just a guide as most of them will be classified.
Tank vs KE (mm)(1) vs CE (mm)(1)
T-34/85 90 110
T-10M Turret: 240-260
Glacis: 240
Lower front hull: 140 Turret: 250-350
Glacis: 250
Lower front hull: 150
T-54/55 Turret: 230 (6)
Glacis: 190 same?
M-46 Turret: 96-108
Glacis: 126-146 same?
M-47 Turret: 130-220
Glacis: 160-200 same?
Centurion Turret: 115-150
Glacis: 140 same?
Centurion Mk6/2 Mantle: 200-230
Turret: 190-200
Glacis: 260
Lower front hull: 130 same?
Conqueror Turret: 350
Glacis: 260 same?
M-48 Mantle: 200
Turret: 170 Glacis:220 same?
M-60A1 Turret: 210
Hull front:170-250 (5) Turret: 250
M60A1 ERA Turret: 260 Turret: 510
M-60A2 Turret: 277
Hull front: 170-250 same?
M-60A3 Turret: 240
Hull front:170-250 Turret: 260
T-55AM2 w/BDD Turret: 180-520 Glacis: 330
Lower front hull: 180 Turret: 190-480 Glacis: 420
Lower front hull: 180
Leopard 1 Turret: 180-200 Glacis:140 Turret: 200-270
Glacis: same?
Leopard 1A1A1 (1975+) Turret: 220-250 (320-450 vs 1970s APFSDS) Glacis:140 Turret: 450-480
Glacis: same
Leopard 1A3/A4 Turret: 250-330 Glacis:140 Turret: 300-400
Glacis: same
Leopard 1A5 Turret: 430-470 Glacis:140 Turret: 450
Glacis: same
Leopard C.2 Turret: 550-600
Glacis: 250-300 Turret: 800
T-62 Front turret: 180-240
Glacis: 210
Lower front hull: 180 (7) Turret: 190-260
Glacis: 210
Lower front hull: 180
T-62E w/BDD Turret: 180-480
Glacis: 350
Lower front hull: 180 Turret: 190-500
Glacis: 430
Lower front hull: 180
T62MV w/ERA Turret: 210-280
Glacis: 240-260 Turret: 680
Glacis: 600
Chieftain Turret: 340-360
Glacis: 350
Lower front hull: 320mm Turret: 380-400
Glacis: 360
Lower front hull: 330mm
M1 (2) Turret: 400 Glacis: 400 Turret & Glacis:700-800
M1IP / M1A1 (2) Mantle & Turret: 450
Glacis: 350-490
Lower front hull:430-470 Mantle: 990 Turret: 800 Glacis:510-800
Lower front hull: 570-790
M1A1HA (2) Turret: 660-680 Glacis:560--590
Lower front hull:580-630 Turret: 1080-1320 Glacis:510-800
Lower front hull:800-900
M1A1HC/M1A1HA+/M1A2 Turret: 880-900 Glacis:560-590
Lower front hull:580-650 Turret: 1310-1620 Glacis:510-1050
Lower front hull:800-970
M1A2 SEP (2) Turret: 940-960 Glacis:560-590
Lower front hull:580-650 Turret: 1320-1620 Glacis:510-1050
Lower front hull:800-970
Leopard 2A1-A3 (16) Turret: 570-630
Glacis: 350 (500-550 vs Soviet 1980s APFSDS)
Lower front hull: 350 Turret: 810-1100
Glacis:520
Lower front hull: 520
Leopard 2A4 Turret: 590-690 Glacis:600
Lower front hull:600 Turret: 810-1290 Glacis:710
Lower front hull:710
Leopard 2A5 Turret: 850-930 Glacis:620
Lower front hull:620 Turret: 1730-1960 Glacis:750
Lower front hull:750
Leopard 2A6 Turret: 920-940
Glacis: 620 ?
Chieftain Stillbrew Turret: 530-540 (580-600 vs 1970s Soviet APFSDS)
Glacis: 300-400 Turret: 730
Glacis: 350-400
Challenger 1 (15) Turret: 590-620 Glacis:550-600
Lower front hull: 450 Turret: 970-1120 Glacis:800
Challenger 2 (21) Turret: 920-960 Glacis:660
Lower front hull: 590 Turret: 1450-1700 Glacis:1000
Lower front hull: 860
T-72 "Ural" Turret front: 280-380
Glacis: 305 Turret front: 280-410
Glacis: 405
T-72 "export" (9)/T-72M (10) Turret: 280-380
Upper front turret: 180
Glacis: 335
Lower front hull: 200 Turret: 280-410
Upper front turret: 200
Glacis: 450
Lower front hull: 200
T-72M1 (11) Turret: 280-380
Upper front turret: 290
Glacis: 400
Lower front hull: 250 Turret: 490
Glacis: 490
T-72A "Dolly Parton" Turret: 280-380
Upper front turret: 290
Glacis: 400(18)
Lower front hull: 250 Turret: 490
Upper front turret: 360-370
Glacis: 490
Lower front hull: 250
T-72B & S w/ERA Turret: 280-540
Glacis: 485
Lower front hull: 250 Turret: 580-850
Glacis: 670-910
Lower front hull: 250
T-80 Turret: 280-450
Upper front turret:200 Glacis:335
Lower front hull:210 Turret: 330-490
Upper front turret:220
Glacis:420
Lower front hull:210
T-80B Turret: 280-500
Upper front turret:290-320 Glacis:415
Lower front hull: 270-360 Turret: 450-640
Upper front turret:340-370 Glacis:490
Lower front hull: 320
T-80BV (8) Turret: 280-530
Glacis: 425-435
Lower front hull: 270-360 Turret: 750-1040
Glacis: 670-910
Lower front hull: 380
T-80U (3) Turret: 280-850
Upper front turret: 290-390
Glacis: 780
Lower front hull: 310-430 Turret: 960-1450
Upper front turret: 700-730
Glacis: 1080
Lower front hull: 500
Ukrainian T-84 w/K-5 ERA Turret: 850-1100
Glacis: 680-720 Turret: 1250-1600
Glacis: 960-1040
T-72BM / T-90 (4) Turret: 420-750-920
Glacis: 670-710
Lower front hull: 240 Turret: 580-1050-1340
Glacis: 990-1070
Lower front hull: 380
T-64 Turret: 280-400
Glacis: 335 Turret: 330-500
Glacis: 420
T-64A (17) Turret: 280-450
Upper front turret: 200
Glacis: 335
Lower front hull: 200 Turret: 330-510
Upper front turret: 190-290
Glacis: 420
Lower front hull: 200
T-64B (17) Turret: 280-450
Upper front turret: 280-300
Glacis:415
Lower front hull: 230 Turret: 380-600
Upper front turret: 420
Glacis:490
Lower front hull: 260
T-64BV (8) Turret: 300-480
Upper front turret: 310-350
Glacis: 460
Lower front hull: 280 Turret: 950-1080
Upper front turret: 850-870
Glacis: 910
Lower front hull: 420
Leclerc (19) Turret: 800 Glacis: 600 Turret: 1400-1750 Glacis 1060
AMX-30 Turret: 180-230
Glacis: 220-240
Lower front hull: 140 Turret: 380
Glacis: 260
Lower front hull: 140
AMX-30B2 (12) Turret: 180-260 Glacis:220-240
Lower front hull: 140 Turret: 200-450
Glacis: 265
Lower front hull: 140
C1 Ariete (13) Turret: 490-500
Glacis:470 Turret: 890-1100
Glacis:780
Arjun Turret: 500-570
Glacis: 410 Turret: 650-830
Glacis:730
Al Khalid Turret: 645
Glacis: 435-455 Turret: 1060 (1160 w/ERA)
Glacis: 540 (670w/ERA)
Japanese Type-74 Turret: 230
Glacis:120 same?
Japanese Type 90 (14) Turret: 800-840 Glacis:420 Turret: 1430 Glacis:670
Chinese Type-59/69/79 Turret: 200-260
Glacis: 195 same?
Chinese Type-59D w/ERA Turret: 200-520
Glacis: 200-490 Turret: 200-800
Glacis: 200-600
Chinese Type-80/88A/B Turret: 280-340
Glacis: 270 Turret: 430
Glacis: 300
Chinese Type 85-III/88C/96 Turret: 400
Upper front turret: 260
Glacis: 400 Turret: 610
Upper front turret: 270-280
Glacis: 480
Chinese Type 98 Turret: 640
Glacis: 450 Turret: 750
Glacis: 560
Chinese Type-99 w/ERA Turret: 740-800
Glacis: 450-630 Turret: 1050
Glacis: 560-860
Merkava Mk1 Turret front: 550 (520 vs 1970s Soviet APFSDS)
Glacis: 380 (540 vs 1970s Soviet APFSDS) Turret front: 800
Glacis: 470
Merkava Mk2 Turret front: 760
Glacis: 480 (570 vs 1970s Soviet APFSDS) Turret front: 1150
Glacis: 600
Merkava Mk3 (20) Turret: 790-820
Glacis: 760
Lower front hull: 670 Turret: 1530-1650
Glacis: 1380
Lower front hull: 1130
Merkava Mk4 Turret: 600-1030 Turret: 750-1340
Magach 7 170-250 170-550
Magach 7C Turret: 360-380
Glacis: 400-430 Turret: 940
Glacis: 570
Magach 7D Turret: 380-520
Glacis: 400-430 Turret: 850-1250
Glacis: 570
Strv-103 300-320 480-620
Strv-103C 300-440 480-820
Strv-122 700-1100 1000-1800
Korean K1 (initial) 480-520
Korean K1 (later) 540-580
Korean K1A1 720-750 1000
Swiss Pz61/68 Turret: 240
Glacis: 115 Same?
M2A2/A3 Bradley Glacis: 130
Front turret: 100-110 Glacis: 150
Front turret: 126
Sources: Mainly from posts on Tanknet the premier source of tank discussion online. Also from Stephen Zaloga's various works on Russian MBTs, GSPO forum, Hilmes' books, Hunnicutt Patton and Abrams, Janes IDR and the NII Stali website.
Notes:
1. I have listed the best frontal armour equivalent, even the mighty M1A2SEP will not have the same protection at all points on its frontal arc. Some points will be weaker, especially say the upper front turret or the gun mount. In many cases the measured LOS armour thickness will differ from the protection estimated above, often that is because of the incorporation of exotic compounds that offer better protection than an equivalent weight of RHA. For example, the LOS thickness of the glacis armour on the basic T-72 is about 550mm, but RHAe protection is far less.
2. Protection levels for US MBT's are larger than usually quoted because the US standard is for a 30 degrees oblique shot. To return to US Army style measurements divide all figures on chart by 1.15 NII Stali estimate M1A1HA turret at 700mm versus KE, 850mm versus CE for a 30 degrees oblique shot. GSPO/BTVT estimates M1A1 at 480-500 versus KE and 790-840 versus CE, M1A1HA at 530-55 versus KE and 750-780 versus CE, M1A2 at 770 versus KE and 1000-1200 versus CE.
3. The quoted figures are with Kontakt-5 ERA i.e T80U or late 1980s T80UD version. Without K-5 protection is turret 275-750mm vs KE and 960mm vs CE. BTVT estimates T80U w/K-5 at 780 versus KE and 1320 versus CE.
4. These figures include Kontakt-5 second-generation ERA. Estimates without ERA are 550mm-720mm vs KE. BTVT estimates T90 at 800-830 versus KE and 1150-1350 versus CE.
5. Turret side is 138mm; turret rear 58mm. M60A1 turret reportedly suffered from substandard cast armour reducing protection offered. This was rectified in M60A3.
6. Turret side is 160mm. Hull side is 80mm.
7. Turret side is 170mm. Hull side is 80mm.
8. Includes Kontakt-1 first-generation ERA.
9. "Monkey model" sold to WarPac/Third World clients with stereoscopic coincidence rangefinder and lower grade steel armour. Used by Iraq in 1991 Gulf War firing poor quality steel 125mm rounds.
10. "Monkey model" sold to WarPac/Third World clients with laser rangefinder and lower grade steel armour. Used by Iraq in 1991 Gulf War firing poor quality steel 125mm rounds.
11. "Monkey model" sold to WarPac/Third World clients with laser rangefinder and glacis applique plate (after tests showed M-111 could penetrate old glacis) plus "sandbar" armour in turret front.
12. With ERA fitted becomes 250-290mm vs KE & 580-720mm vs CE.
13. Turret side is 140mm vs KE & 220mm vs CE. Uparmoured Ariete is 570-600mm turret vs KE and 1140-1360mm turret vs CE.
14. Turret side is 290mm vs KE and 450mm vs CE.
15. Lower hull front of Mk1/3 version had ERA = 520mm KE & 800-1000mm vs CE. Side hull had ERA = 130mm KE & 820-840mm vs CE.
16. Some Russian estimates give the Leopard 2 frontal protection of 700mm vs KE and 850mm vs CE. See
http://armor.kiev.ua Others estimate Leopard 2 as 380-400 versus KE and 650-700 versus CE. BTVT estimates Leopard 2A4 (1988) at 580 versus KE and 1100 versus CE and Leopard 2A5 (1994) at 830 versus KE and 1300 versus CE.
17. According to a declassified CIA report from 1984, the US then assessed that the T-64A and T-64B had the same protection level of 370-440mm vs KE and 500-575mm vs CE. NII Stali estimated the T-64A glacis as 299 KE/410 HEAT and the turret as 364 KE/450 HEAT RHA equivalent protection. The T-64 was designed to be protected against all 1960s 105mm ammunition. Original T-64A turret was 150mm steel +150mm aluminium alloy + 40mm steel; glacis was 80mm steel + 105mm fibreglass + 20mm steel. GSPO estimates T-64B as 380-450 versus KE and 500-560 versus CE.
18. Glacis figures after applique plate applied. Original glacis of 335mm RHAe could be penetrated by M-111.
19. Russian estimate gives Leclerc turret 620-640 versus KE; 1100-1200 versus CE. French estimate gives it 650-700 versus KE and 1100-1200 versus CE.
20. Russian estimate gives Merkava Mk3 turret 580 versus KE; 1200 versus CE.
21. Russian estimate gives Challenger 2 turret 800 versus KE; 1300 versus CE.
AT Round penetration estimates:
(please be aware there is a good margin of error around any of these figures)
Israeli/Chinese (new) 125mm 640mm at 2km
Pakistani Niaza 125mm DU 550mm at 2km
Israeli 125mm 560mm at 2km
Chinese/Pak (old) 125mm tungsten 460-480mm at 2km (1993)
Ukraine 125mm Vitiaz round 760mm at 2km (2002)
Russian 125mm BM-4? tungsten 800mm at 2km (200?)
Russian 125mm BM-42M tungsten 600mm at 2km (1991) (22:1 L/D)
Russian 125mm BM-42 "Mango" tungsten alloy 520mm at 2km (1988) (16:1 L/D)
Russian 125mm BM-32 "Vant" DU 560mm at 2km (1985) (13:1 L/D)
Russian 125mm BM-29 DU 500mm at 2km (1982) (12:1 L/D)
Russian 125mm BM-26 (1983) tungsten alloy 490mm at 2km (extended BM-22 13:1 L/D)
Russian 125mm BM-22 "Hope" (1980 - some say 1976) tungsten 470mm at 2km
Russian 125mm BM-17 (1970) steel 250mm at 2km (simplified export BM-15)
Russian 125mm BM-15/Yugo M88 tungsten (1968) 380mm at 2km (version of BM-12 with extended projectile)
Russian 125mm BM-12 tungsten carbide (1968) 350mm at 2km
Russian 125mm BM-9 steel (1962) 290mm at 2km
Russian 125mm BK-12 HEAT (1962) 420mm at all ranges
Russian 125mm BK-18 HEAT (1980) 550mm at all ranges
Russian 125mm BK-29 HEAT (1990) 700mm at all ranges
Indian T-2A 125mm tungsten 500mm at 2km (1997) (appears similar to ChiCom 125mm round)
Iranian 125mm tungsten 470mm at 3km
Polish Pronit 125mm tungsten 540mm at 2km (2001)
1990s Polish 125mm tungsten round 460mm at 2km
Czech Synthesia 125mm APFSDS-T round 500mm at 2km
Slovak TAPNA 125mm APFSDS-T round 530mm at 2km
Soviet 122mm BR471B APBC 147mm at 1km (129mm at 2km) (1945)
Soviet 122mm BR-472 APBC fired from JS-III 191mm at 1km (165mm at 2km)
Soviet 122mm BR-472 APBC fired from T-10M 247mm at 1km (210mm at 2km)
Soviet 122mm BM11 APDS fired from T-10M 354mm at 1km, 308mm at 2km (1967)
German 120mm DM-13 390mm at 2km (1979)
German 120mm DM-23 470mm at 2km (1983)
German 120mm DM-33/Japanese JM-33 550mm at 2km (1987)
German 120mm DM-43A1/US KEW A1 590mm at 2km (1994)
German 120mm DM-53 tungsten 700mm at 2km (1996)
German 120mm/L55 DM-53 760mm at 2km (2001)
German 120mm DM-63/Israeli M-338 tungsten 680mm at 2km (2006)
German 120mm/L55 DM-63 tungsten 720mm at 2km (2006)
S.Korean K276 120mm tungsten 700mm at 1km (2004)
French 120mm OFL120F1 tungsten 590mm at 2km (1994)
French 120mm OFL120F2 DU 647mm at 2km (1997)
US M103 120mm APC 221mm at 1000yards; 199mm at 2000yards at 30 degrees
UK Conqueror 120mm AP 255mm at 1000 yards; 226mm at 2000 yards (1.8km)
UK L-15 120mm APDS round 355mm at 1km/340mm at 2km (1965)
UK L-23 120mm APFSDS round 450mm at 2km (1984)
UK L-26 120mm APFSDS round 530mm at 2km (1989)
UK Charm-3 L-27 APFSDS 120mm DU 720mm at 2km (1998)
UK L-28 120mm APFSDS 770mm at 2km (200X)
US M829A3 120mm DU 765mm at 2km (2003) (Russian estimate 795mm)
US M829A2 120mm DU 730mm at 2km (1994)
US M829A1 120mm DU 610mm at 2km (1991) (Russian estimate 700mm)
US M829 120mm DU 552mm at 2km (1988)
US M827 120mm DU 450mm at 2km (1986)
US Olin GD120 120mm tungsten 520mm at 2km
US/Egyptian KEW-A2 120mm tungsten 660mm at 2km
South Korean 120mm APFSDS 670mm at 2km
Indian 120mm tungsten 650mm at 2km
Chinese 120mm tungsten 550mm at 2km
Russian 115mm BM-28 DU APFSDS 384mm at 2km (early 1980s)
Russian 115mm BM-21 DU APFSDS 330mm at 2km (mid-late 1970s)
Soviet 115mm BM-6 steel APFSDS 280mm at 1km, 246mm at 2km (1962)
Soviet 115mm BM-3 tungsten carbide APFSDS 270mm at 2km (for original T-64)
UK/Egyptian 115mm BD/36-2 APFSDS 460mm at 2km
Chinese Type-86 105mm DU 460mm(from "short" 105)/480mm(from "long" 105) at 2km
Chinese Type-93 105mm DU 510mm("short")/540mm("long") at 2km
Chinese Type-95 105mm DU 580mm at 2km (from "long" Type-83A 105mm)
UK T-2 HP 105mm tungsten round 560mm at 2km
UK 105mm L-28 tungsten cap APDS 120mm at 60 degrees at 900m, 250mm at 1km (mid-1950s)
US 105mm L-36A1/M392 tungsten cap APDS 260mm at 1km (1960s)
UK 105mm L-52A3 tungsten core APDS 320mm at muzzle, 280mm at 1km, 254mm at 1500m, 240mm at 2km (1973)
UK 105mm L-64A4 tungsten APFSDS 310mm at 2km (1982)
UK/Pakistani 105mm H6/62 APFSDS 360mm at 2km (1990s)
Pakistani 105mm DU APFSDS 450mm at 2km
Indian 105mm APFSDS 350mm at 2km
French OFL105F2 105mm DU 520mm at 2km (mid 90s)
French OFL105G1 105mm APFSDS 350mm at 2km (1981)
French OFL105G2 105mm tungsten 440mm at 2km (late 1980s)
French OFL105F1 105mm tungsten 250mm at 2km (1981/2)
French 105mm HEAT (AMX30) 160mm at 60 degrees
Canadian C127 105mm tungsten 460mm at 2km (1992)
US M-392A2 105mm APDS 260mm at 1km, 250mm at 1.5km, 225mm at 2km (early 1970s) (Rushed into service after M392 problems in 1973 Arab-Israeli war)
US M-728 (UK L-52) 105mm APDS 320mm at muzzle, 280mm at 1km, 240mm at 2km (mid 1970s)
US M-735 105mm tungsten APFSDS 330mm at 1km, 300mm at 2km (1978)
US M-735A1 105mm DU 370mm at 1km, 350mm at 2km (never deployed)
US M-774 105mm DU 375mm at 2km (1981)
US FP105/Can C76 105mm tungsten 330mm at 2km (export only)
US M-833 105mm DU 440mm at 2km (1984)
US M-900 105mm DU 520mm at 2km (1991)
Taiwanese TC84 105mm APFSDS 450mm at 2km
Mecar 105mm tungsten APFSDS 390mm at 2km
German DM-23/Israeli M111 105mm tungsten 310mm at 2km or 150mm at 60 degrees (1978)
German DM-23A1 105mm tungsten 330mm at 2km (1980s)
German DM-33/Israeli M413 105mm tungsten 380mm at 2km (1984)
German DM-63/Israeli M426 105mm tungsten 450mm at 2km (early 1990s)
US M456 105mm HEAT 350mm
Soviet BM-25 100mm APFSDS 296mm at 2km (late 1970s) [320mm at 1km]
Soviet BM-8 100mm APDS 238mm at 2km (1968) [257mm at 1km]
Soviet 100mm HVAPDS 200mm at 1km (HEAT 300mm)
Soviet BR-412D 100mm APCBC 198mm at 1000m (165mm at 2000m) (post-war)
Soviet BR-412B 100mm APBC-T 160mm at 1000m (134mm at 2000m) (1945)
Soviet 100mm BK-354M HEAT 280mm (WWII)
Soviet 100mm BK-5M HEAT 390mm (1960s)
Yugoslav M65 100mm APCBC 158mm at 1km; 136mm at 2km (1954)
Yugoslav M98 100mm APFSDS 150mm at 60 degrees at 2km
Pakistani/Chinese AP-100-2 100mm APFSDS 350mm at 2km (1986)
Chinese AP-1 100mm APFSDS 240mm at 2km (1980)
Chinese AP-2 100mm APFSDS 290mm at 2km (early 1980s)
Romanian BM-412M (M309) 100mm APFSDS 418mm at 2km (1990s)
Mecar M-1000 100mm APFSDS 350mm at 2km (1996)
US 90mm T-65 APDS 195mm at 1000 yards at 30 degrees
US 90mm T-33 APBC 220mm at 1km
US 90mm M318 AP-T 189mm at 1km
US 90mm M304 HVAP 250mm at 1000m, 220mm at 1500m (1945)
US 90mm M82 APCBC 140mm at 1000 yards (913m)
90mm M77 AP 166mm at 500 yards
Mecar M-652 90mm APFSDS 180mm at 1km (150mm at 2km)
French OFL-90 F1 90mm APFSDS 230mm at 1km (200mm at 2km) (early 1980s)
South Korean M-241 90mm APFSDS 230mm at 2km (1984)
UK 20pdr APDS 280mm at 1000 yards (913m) [260mm at 1500 yards]
Soviet 85mm BR367 APHE 163mm at 1km
Soviet 85mm BR365PK HVAP 180mm at 1km; 150mm at 1500m
Soviet 85mm BR365K APBC 128mm at 1km (1944)
US M93 76mm HVAP 175mm at 1000m, 160mm at 1500m (1945)
Soviet 76.2mm HVAP 61mm at 1km (HEAT 120mm)
US 76mm M464 APFSDS 230mm at 2km
Fr 75mm POT-51A (Isr M50) 110mm at 1km
Soviet 57mm BR-271P HVAP 145mm at 500m
Bofors 40mm APFSDS 131mm at 1km
35mm APDS 90mm at 1km
Oerlikon 30mm APFSDS 97mm at 1km
30mm L14A3 tungsten APDS 63mm at 1km
2A42 30mm AP-I 44mm at 1km
2A42 30mm APDS 62mm at 1km
New 2A42/2A72 30mm APFSDS 79mm at 1km
25mm APFSDS DU 75mm at 1km
Oerlikon 25mm tungsten APFSDS 77mm at 2km
25mm APFSDS 56mm at 1km
20mm APDS DM-63 44mm at 1km (1988)
20mm APDS DM-43 40mm at 1km (1982)
20mm HVAP for Rh-202 gun 34mm at 1km
12.7mm API 19mm at 500m
http://members.tripod.com/collinsj/protect.htm