The Grainger Approved Bumper is a rubber bumper designed to absorb shock and reduce noise from impacts. It has a 2-1/2" diameter, is 3/4" thick, and has a 1/4" diameter center hole. The bumper is made of SBR rubber which provides good abrasion resistance. It can be used in a variety of applications including material handling equipment, conveyors, and industrial machinery to protect components from damage. The bumpers come in packs of 4.