Safety Series Chair Mat Casters, Standard Neck, 3/8" Dia. x 7/8" Long Stem, 110 lbs./Caster, Matte Black Finish, 5/Set (65534) Patented Roll Control Internal brake prevents wheels from rolling freely when user stands. Allows smooth effortless chair rolling while seated. 2" diameter dual hooded wheels. 5/8" standard size dia. neck. Soft polyurethane wheels for use on chair mats and hard floor surfaces. 3/8" dia. x 7/8" long stem fastener for metal bases. Weight Rating: 110 lbs/Caster. Matte Black Finish, 5/Set