5/8-11 X 4 Hex Head Tap Bolt GR5 Zinc PlatedA tap bolt is a fully threaded fastener (often hex headed) designed to screw directly into a pre tapped (threaded) hole acting like a combination of a bolt and a tap (threading tool) to create strong precise connections without needing a nut on the other end ideal for machinery automotive and structural uses where space is tight or a flush finish is needed.