This is an APC NetShelter SX server rack enclosure, a full-height 48U cabinet (the tallest common rack size, holding significantly more equipment than a 24U cabinet) with a wider-than-standard 750mm frame and a deep 1200mm body. The extra width and depth give more room for cable management and airflow around densely packed servers, switches, and cabling — the NetShelter SX range is specifically designed for high-density data center and server-room deployments rather than light office use. It's typically bought by businesses consolidating many servers/network devices into a single, well-organized, well-cooled cabinet rather than scattering equipment across shelves.