Standar Duty Casters feature a soft gray rubber wheel molded to a polypropylene hub with an oil-less bearing. Style A is a 3” fixed caster with a 2-1/2” x 2-3/4” mounting plate with a 155 lb. load bearing rating. Style B is a swivel caster with a single wheel lock system and is rated for 155 lbs, and has a 2-1/2” square mounting plate. Style C is a swivel caster with a double locking brake system (swivel & wheel) is rated for 255 lbs. with a 3/8” x 1” post for easy mounting. All casters are 4” in height. Mounting hardware not included.