The Simpson Strong-Tie GCT is a preassembled MEP (mechanical, electrical and plumbing) fastener designed to secure zip ties to concrete. The versatile GCT assembly consists of a preassembled zip-tie holder attached to a 1" smooth-shank fastener. This tie-strap holder is for high-volume applications and works with gas-actuated concrete nailer tools as well as with common powder-actuated tools for fastening into harder substrates (structural steel or extra-hard concrete) when required.