Middle Atlantic SH-WR The Middle Atlantic SH Series Zero Space Rack Shelf SH-WR is a space-saving, 16-gauge steel, rack shelf that offers a secure space for non-rackmount components. The shelf mounts to the sides of the rack rails instead of the threaded rack-rail face, providing more useable shelf area. Two versatile L brackets are also included to help perfectly position your equipment. The shelf features a durable, black, powder-coat finish and all mounting hardware is included. This unit is designed for use with WR racks.