My tub, as purchased, came with "2 sides" included. I could have two- or three-tiered steps, or steps on one side and a bar and stools on the other. The steps can be narrow or (as mine are) wide and the corner piece my dealer was nice enough to provide as well. I chose the three tiered step because it makes it *so* much easier to get in and out, and I think just happens to look nicer, too.
I see no reason they could not be ordered for any tub. The "long" steps like mine are 70 3/4" long, 11" deep each.