Provides centered loading for deeper and heavier equipment. Mounts on 3″D (80 mm) double-sided racks only. Mounting hardware not included. 19″ version holds equipment up to 17.75″W x 21.5″D (450.9 mm x 546.0 mm), 23″ version holds equipment up to 21.75″W x 21.5″D (552.5 mm x 546.0 mm). Made of strong, lightweight aluminum; supports up to 100lb (45.4 kg).