This adapter allows you to use the Gen 1,2, & 3 recoil spring assembly on your Gen 4 Glock. The insert is made from steel and is black anodized to match your Glock. Fits all Gen4 Glocks.
Good quality product, however it does not work well in the G41 using a ZEV ss guide rod.. Slide does not fully retract when paired with the ZEV stainless guide rod. It binds about 2/3 of the way back. I tried it with some other SS guide rods and it works a bit better. It is not the fault of the adapter, it's a guide rod and spring issue in the G41. In other gen 4s this would be ideal and an excellent choice for tuning your RSA to your loads.