This screen retainer spline is constructed of top quality vinyl that is round in shape. It features a hollow core center, it is serrated on its exterior surface, and it is black in color. Vinyl screen retainer spline like this one is used to hold fiberglass and aluminum screen material to screen frames of both windows and doors. This retainer spline has an outside diameter of .165 (11/64 in.) and measures 25 feet in length.