This is a "K" tab patio door roller assembly with a 1-1/4 in. concave or grooved plastic ball bearing roller. The "K" tab style back end is a T shaped tab that is simply slid up into a similar 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 dimple width of 3/4 in. Used by International and a variety of other sliding patio door manufacturers.