One end is 5mm (approx. 3/16") female which attaches to Badger airbrushes which have a 5 mm male connection. The other end with 1/8" BSP male threads attaches to Grex, Olympos, Iwata and Harder Steenbeck air hoses. Precision machined of metal for durability. Electro-plated for a smooth easy to clean surface.