Gear Head Works AR-15 Carbine Spring and Buffer Black. 15 in Weight: 0.35 lb Package Contents: Gear Head Works AR-15 Carbine Spring and Buffer What firearm models does the manufacturer say Gear Head Works AR-15 Carbine Spring and Buffer is compatible with? The manufacturer suggests that Gear Head Works AR-15 Carbine Spring and Buffer is compatible with AR-15Gear Head Works GHW-37: AR-15 Carbine Spring and Buffer Black