Extruded aluminum bracket with glazing vinyl. Accepts up to 1/4 In. thick panels, 3/4 In. outer diameter with an oval edge nylon ball bearing roller. Used on solid glass panels with no frame. This 2-piece assembly clamps onto the top of the shower door glass with a vinyl glazing gasket. It will fit up to 1/4 inch thick glass. The nylon roller height is adjustable by sliding the roller up or down in the diagonal mounting slot and then tightening.