[6t8stang]

I believe mine locks every 4 inches, but are adjustable 2" in either direction, so essentially you can set the locks to just about any height. Keep in mind you'll need room above your lock to disengage (you'll have to lift off the locks a little to release). Mine did come with casters - haven't had to use them yet. Instructions say you don't have to bolt it to the floor unless you're raising/lowering several times every day - the hobbyist doesn't need to be bolted down. Mine shifts ever so slightly when going up/down, but hasn't really moved out of position.

I also bought a sliding jack for between the rails, but other than playing, haven't used it yet. One disadvantage of the 4 post is the rails do get in the way sometimes - especially when working on brakes/suspension. Many times for these it's easier to use the old floor jack and mechanics chair. However, one of my goals was to use for storage too, which I don't believe is recommended for the 2 post. I also didn't want to trust my concrete was thick enough for the 2 post.