NUMBER ZDM-HDSTAND Bench Head Stand Set Aluminum & Steel Heads This Head Stand set has been designed for use on most cylinder heads. In operation, it holds the head off the bench for valve work, head cleaning and assembly. Its holding rods have a log 5 inch taper which allows them to go further into the stud hole for more contact in the hole and a firmer grip on the head. These holding rods are also heat treated to remain smooth for use on aluminum heads.