Canister filled with steel shot in the hammer's head creates a dead blow effect to reduce rebound; Dead blow design also sustains impact, maximizes force, and absorbs the shock of impact; Non-sparking, hot-cast polyurethane body covers the steel shot chamber and the steel reinforced handle; no exposed metal; Slim-profile polyurethane face doesn't mar surfaces or absorb liquids, and reduces striking noise from hitting slugging or striking wrenches; Steel reinforced handle is strong and safe, built to resist breaking from an overstrike; Knurled texture on the handle with a flanged back end combine for a sure non-slip grip; Red polyurethane body is highly visible and durable enough for heavy-duty work, designed to resist chipping or splitting; Meets or exceeds US federal spec. GGG-H-33A