Simpson GW50-R200 1/2" Dome Washer And 1/2" Step Shank Pin w/Fuel Cell, Pkg 200The Simpson Strong Tie GW is a gas actuated 1 2" dome washer pin designed to fasten building components to concrete. The versatile GW consists of a 1 2" dome washer and a pin of 1 2", 3 4" or 1" in length. The GW is for high volume applications and can be used with common powder actuated tools for fastening into harder substrates (structural steel or extra hard concrete) when required.