Heavy duty ¾”-6 ACME screw thread. Large 1.4” contact pad diameter. Sized to work with the bed height of a standard 6” milling vise. Brass locking mechanism. The base can be bolted to the mill table. (5/8” T-nut included) Contact pad has a 0.251” hole with 10-24” treads that can be used for custom applications. A spacer kit is available (sold separately) to allow the Machinist Jack to work with a standard 6” vise that is mounted on a swivel base. The screw and main body are made from hardened steel. *** PLEASE SCROLL DOWN FOR MORE DETAILS. *** The Machinist Jack by Edge Technology is specifically designed for supporting long stock during milling operations. The oversized ACME screw and large contact pad provide ample support for any setup. The ACME screw can be locked in place and the base of the jack can be bolted to the table for even more rigidity. It is sized to work perfectly with a standard milling 6” vise.