I asked this same question a couple pages back. I know I bought 1 based on his answer.

We set ours at 15". My Mojo factory is 9", new unit all the way down is 12".
We love it. So much easier to see and the bolster now supports your legs and my wife does not have to stand. If you get the pin 100% engaged, then tighten the handle all the way, it does not move. We leave the swivel slightly loose so we can rotate, but no other movement.

Install is super easy, phillips screwdriver and about 10 minutes while the family was getting packed for the lake.