CSI Spiral Drive Pins are designed for permanently fastening a fixture to concrete, concrete over steel deck, concrete masonry walls and A36 or A572 / A992 structural steel. The fasteners are manufactured with an 8mm head and 0.157" diameter shank in various lengths; a 0.145" diameter tapered shank with 1/2-inch length is also available. A spiral knurled shank design provides consistent optimized performance in steel base materials. For single fasteners, a plastic washer is mounted on the pin shank to retain the drive pin in the barrel of the tool and provide centered guidance during the driving operation