Made to attach to tubes with a 1.5 to 2" outer diameter and used like a C-clamp, the Kupo Iron Casting Clamp has a 2.5"-long steel shaft with 1/2"-13 yoke bolt and washer. It can support up to 220 lb.
In the Box
Kupo Iron Casting Clamp
2.5" Steel Shaft with 1/2"-13 Yoke Bolt and Washer