SOPMOD
The Special Operations Peculiar MODification (SOPMOD) kit is an accessory system for the M4A1 carbine, CQBR, FN SCAR Mk 16/17, HK416 and other weapons used by United States Special Operations Command (USSOCOM) special forces units, though it is not specific to USSOCOM. The kit allows US Special Operations Forces (US SOF) personnel to configure their weapons to individual preferences and customize for different mission requirements. The SOPMOD kit is composed mostly of non-developmental items and commercial off-the-shelf (NDI/COTS) accessories packaged together to support four M4A1 carbines.