This is a new old stock fitting that goes on the outgoing side of the fan clutch solenoid of the FMTV's. The small nipple breaks easy when working on the air line going to the fan. Shown in the pictures is a broken one. These are new old stock from a bulk lot. I put a small dab of blue thread locker on the small side to help keep it secure. Some fittings have a rubber gasket, others don't. My truck didn't have one & never leaked. Thanks for looking!