We make many different adapters for industrial applications. When you see the term male or female pilot, it means that this part has a feature that guides and aligns a mating part. In this case, it's actually unusual to see two female pilots on the same part. The pilot on the closest part is the rim. On the part directly behind, the pilot surrounds the hole in the middle a recessed area. Pilots usually have a very tight tolerance of .001" (one thousandth of an inch)