These extension units are suitable for operating PTPD pull down clamps and PTNS1 work supports from a distance. Attach an extension bar and hex socket (not included) to connect the extension unit to the clamp or work support. The hex head can be turned manually or operated with an impact wrench. The hex head makes it ideal for use with a nut runner on automated production lines. The body is made from 1045 steel with a black oxide finish. The hex head is made from 4135 steel, quenched and tempered, with a black oxide finish.