The FRAC (Fixed Rear Airline Connector) provides a hard-point airline fitting on your MTW’s sling plate, removing the need to run your airline out your grip and allowing for one-handed connecting/disconnecting of the airline. The fitting is released by pressing the button for easy disassembly of your MTW. The 3.5″ airline with integrated filter helps keep dust and debris out and fits standard MTW M4 and MTW-9.