Shepherd Hardware 9733 2-Inch Office Chair Caster, Twin Wheel, 5/16-Inch Threaded Stem Diameter, 75-lb Load Capacity 2-inch diameter twin wheel black plastic swivel caster with threaded stem mount 5/16-inch x 1-inch stem with 2-1/2-inch or more adjustable clearance height 75-lb load capacity per caster Twin wheels allow for more surface area in contact with the floor and move in opposite directions to minimize carpet fiber twisting - commonly found on RTA furniture, office chairs and entertainment centers Includes 1 caster