This is an Arcadia style roller assembly used by Arcadia doors as well as a variety of other sliding patio door manufacturers. This is currently a very popular design amongst patio door manufacturers in today's market place. It has a wire tension spring and comes with a 1-1/4 in. high density polyethylene roller and fits onto the Prime-Line part B 569 corner insert. Often used on the top as well as the bottom of the sliding screen door. Also look at Prime-Line parts B 541, B 610, B 714, B 736 and B 821 for similar spring tension rollers.