A:
It has a lever on the side to adjust up and down. I think it's 24 inches on the low end, and about 30 on the tall end. I'm about 6'0" and at tallest point, it's more of a lean on seat than a sit on the top. I would only use this for a butt-seat for a front deck casting support.
The base is not the standard 2 3/8", it is more in line with about a 1 1/2" base.