Universal Server Rack Casters | Bolt Pattern: 45mm x 75 mm | Hardware IncludedThis 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.StarTech.com Rack CompatibilityReplacement Casters For:Optional Casters For*:4POSTRACK12URK1224WALHM4POSTRACK25URK1232WALHMRK1233BKMRK1520WALHMRK1833BKMRK2620WALHMRK2433BKMRK616WALMRK2537BKMRK9WALMRK4242BK24RK4242BK30*Optional casters are sold separatelyThe StarTech.com Advantage- 2-INCH CASTER WHEELS: Four pack of universal swivel casters can be used as replacements on portable/mobile 4-post racks such as RK1833BKM, RK2433BKM, RK4242BK24 or to convert a floor rack to a rolling rack when casters are not included- TECHNICAL SPECIFICATIONS: Bolt Pattern: 45x75mm (1.8""""x2.9"""")- Wheel Size: 2""""x1.7"""" (50x43mm)