The Geissele Automatics SOPMOD Certified Series features products that are currently in use by top tier military and counter-terrorism units throughout the U.S. Special Operations Command (USSOCOM). SOPMOD is a USSOCOM program that allows Special Operations personnel to configure their weapons and these items are approved accessories for rifles such as the M4A1 carbine, FN SCAR Mk 16/17, and other weapons used by Special Forces. For this approval the products in this series have gone through rigorous U.S. Government testing and certification by the USSOCOM.