Great item.  Worked perfectly for my pump.  I pre-installed on my 1" pipe and got everything ready to go into the 4" pipe and when I got to the torque arrestor we realized what we guessed was 4" was actually much larger.  My wife loosened the upper clamp until it would slide into the tube and then re-tightened the clamp.  Worked like a charm.  Would buy again if I needed to.  Would recommend fully to anyone needing one of these.  This item will also mount on a 1 1/4" pipe.