This tube insert is designed to be used with a 7/8 heim joint in tubing with a 1 I.D. This tube insert differs from our standard insert because it has a larger O.D. (1 1/2"") at the area to be welded, it is the perfect insert to use if you are using 1/4" wall or thicker tubing. It also has the added benefit of a machined hex making linkage adjustments a much simpler task.