The Simpson Strong-Tie GRH is a preassembled MEP (mechanical, electrical and plumbing) fastener designed to secure 1/4" or 3/8" threaded rods to concrete. The versatile GRH assembly consists of a smooth-shank fastener, with a premounted cold-formed steel bracket that features a threaded hole for the hanging rod. This rod hanger 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.