This pintle pin replaces the pintle bolt on M2 / M3 pintles for the 1919a4, 1917a1, 1919a6 and M2 / M3 50 cal brownings. The pin is made from 4140 pre hardened steel, cnc turned and finished in a hot blue finish. The toggle at the end of the pin rotates to lock the pin in place in use. We arent sure this is USGI in origin, but it is really handy to have. We like ours so much that we invested the time and money to make some.