This AR-15 Hollow Roll Pin Starter Punch Set is made from heat treated steel and gives you all sizes needed to complete your Build. The AR-15 Hollow Roll Pin Starter Punch Set helps to prevent damage caused by slipping off the AR-15 roll pin while getting the pin started on your gun, each roll pin punch has a cavity that the roll pin can rest in to align and start the pin then finish driving it home with flat punch. Punch set is made from heat treated steel and comes with sizes needed to complete AR15 build. Punch inside diameter sizes .130",.100",.086" .067". Works with Trigger guard pin, Bolt catch Forward assist, Gas tube, Bolt ejector and charging handle.