These screw into the M10x1.5 threaded holes in the bottom of the legs. They usually take about two additional weeks because they use a casters of somewhat different design which we do not ordinarily stock. (As of Marc 6, 2017, we have the 3" wheel version in stock.) The 5" wheels add about 6 1/2" to the height of your pier; the 3" wheels add about 4 1/2".
