This Shower Door Tubular Single Sided Towel Bar is constructed of 1.5 mil thick brass tubing. The 3/16 inch (4.76 millimeter) low profile end caps make this towel bar an ideal choice for most by-passing sliding shower doors. It is available in several popular finishes. This shower door towel bar fits 1/4 to 1/2 inch (6 to 12 millimeter) thick glass. It requires two 1/2 inch (12 millimeter) diameter holes. This shower door towel bar is used by several shower door manufacturers.