Reduced height design saves on valuable rack space. Mounts to either front or back of rack channel face. Mounting hardware not included. 19" version holds equipment up to 17.25"W x 18.82"D (438.2 mm x 478.0 mm), 23" version holds equipment up to 21.25"W x 18.82"D (539.8 mm x 478.0 mm). Made of strong, lightweight aluminum; supports up to 40 lb (18.1 kg).