Extra Large Heavy Duty Office Chair Casters 4" Softech Twin Wheel - Hardwood Floor Safe Wheels Set of 5 Thermoplastic elastomer rubber wheels - Safe for ALL floors Non-marking and non-marring - 4-5/16 Mounting Height Extra Large Heavy Duty size 4" (100mm) 225 pound capacity per caster High quality hardwood and laminate floor safe replacement for nylon casters Grip ring stem size: 7/16" diameter; 7/8" length; 4-5/16" mounting height