Extra Large Heavy Duty Office Chair Casters 4" Nylon Twin Wheel - Ideal for Carpet Set of 4 Nylon wheels - Ideal for carpet and floor mats Heavy Duty support - 175 pound capacity per caster Extra Large size 4" (100mm); 4-5/16" mounting height High quality replacement for factory casters Grip ring stem size: 7/16" diameter; 7/8" length