Most likely a a pitot tube
Total pressure is the pressure felt by a surface facing the airstream and is the sum of static and ram pressure. Static pressure is the pressure felt by a surface aligned with the airstream and is like the pressure reported in the weather report. Both are needed to measure the aircraft’s indicated air speed, and the static pressure measures its pressure altitude.
In subsonic flow the air ahead of the aircraft is influenced by the aircraft's pressure field, and at high angles of attack and high wing loadings this reaches out quite a bit. The pitot tube can only measure total pressure when it points into the flow direction. Ahead of the aircraft, the local flow angle increases the closer you are to the aircraft, and this increases measurement errors, because now the pitot tube sits at an oblique angle to the airflow. A longer pitot tube reaches farther out into still relatively undisturbed flow, so less compensation is needed to arrive at good values for total and static pressure. In early flight test, the pitot tube is much longer again, because the compensation factors are not yet established.
They eventually become smaller