Extra deep design is convenient for mounting large equipment requiring additional support. Mounting hardware not included. 19" Version holds equipment up to 17.75"W x 25.8"D (450.9 mm x 655.8 mm), 23" version holds equipment up to 21.75"W x 25.8"D (552.5 mm x 655.8 mm). Made of strong, lightweight aluminum; supports up to 150 lb (68.0 kg). 19" version is UL Listed: File E140851; Category DUXR (US), DUXR7 (Canada) - Communications Circuit Accessory.