The Paratech AcmeThread Struts are comprised of a 2½” diameter Acme threaded aluminum movable solid shaft that extends out of a 3” diameter aluminum tube. The AcmeThread is a square thread that allows full surface contact of the shaft through the collar and the collar full surface contact on the tube to transfer the load directly to the ground. AcmeThread Struts can be extended manually or pneumatically with air, carbon dioxide, or nitrogen.