Ergo Grip Original SUREGRIP, Fits AR-15/M16, Black 4010-BK The ERGO 2 AR Pistol Grip with SUREGRIP is uniquely designed to allow installation on both .556 and .308 AR/M4 lower receivers without a need for spacer inserts. A traditional A2 sized inner cavity is compatible with many accessories available on the market. The ergonomically correct finger grooves provide a sure purchase under even the most extreme conditions. Each ERGO Grip comes with their patented GAPPER and uses existing grip hardware for installation.