The Middle Atlantic Cage-Nut Style Rackrail Kit WRK-RR24 is designed as an alternative to the standard 11-gauge, 10-32 threaded rackrails included in the WRK Series of racks. Each 42'H (24U) rackrail has a cable pass-through feature that allows wires to be laced along its sides with cable ties. Cage nuts and rack screws must be purchased separately. This model is made specifically for WRK 24U racks.