APC by Schneider Electric NetShelter 4 Post Open Frame Rack 44U Square Holes. Open rack system for easy access to IT equipment and cabling. 4-Post Open Frame Racks provide simple, low cost mounting means for rack-mount equipment in IT environments. Ideal for rack-mount servers, networking, and telecom equipment where security at the individual rack level is not required, open frame racks provide unobstructed airflow and fast, easy access to installed equipment. Provisions for vertically mounting Rack PDUs in the rear combined with options for easily routing, organizing, and storing large bundles of cables make Schneider Electric 4-Post Open Frame Rack solutions the best alternative on the market. Customers can choose either the open frame rack with square mounting holes for server applications (many servers today require square mounting holes), networking, and telecom applications or the open frame rack with threaded mounting holes for networking and telecom applications. APC by Schneider Electric. NetShelter 4 Post Open Frame Rack 44U Square Holes. Service & Support Type. 5 Year Repair or Replace.