This set of four M6 2-inch casters, while designed for StarTech.com racks, can be added to the bottom of any server equipment rack, network rack, A/V rack, etc. with a 45mm x 75mm bolt pattern. Ideal for replacing damaged casters or upgrading a standing rack to a rolling rack for additional mobility. RKCASTER2 is backed by a lifetime warranty and free technical support. Replacement Casters For: 4POSTRACK12U 4POSTRACK25U RK1233BKM RK1833BKM RK2433BKM RK2537BKM RK4242BK24 Optional Casters For RK1224WALHM RK1232WALHM RK1520WALHM RK2620WALHM RK616WALM RK9WALM RK4242BK30 More from the Manufacturer