This is a "K" tab patio door roller assembly with a 1-1/4 in. concave or grooved steel ball bearing roller. The "T" shaped tab (K-Tab) is simply slid up into a T shaped receptacle in the bottom of the patio door. No screws are required. The housing is 5/8 in. wide and 1-3/16 in. tall with a flare and a 3/4 in. dimple width. Used by International and a variety of other sliding patio door manufacturers. Color: Stainless Steel.