extra large heavy duty office chair casters 4" nylon twin wheel - ideal for carpet set of 5 shepherd service caster listing is for set of 5 (five) ultima heavy duty furniture and light equipment twin wheel casters with 4" (100mm) nylon wheels and grip ring stems. an excellent choice for replacing cheap factory nylon body and wheel casters. dependable twin wheel caster for chairs, tables, plant stands, ottomans, furniture and light equipment where an easy rolling, heavy duty caster is required for carpet and mats. provides optimum performance on all furniture, medical equipment carts, hospital supply carts, computer carts, display stands and much more. 175 pound capacity per caster, with a 4-5/16" mounting height. grip ring stem size: 7/16" diameter; 7/8" length.