1-5/8" (40mm). Twin wheel U-bracket caster. Black. This caster offers an economical and reliable solution. The 2 wheels move in opposite directions when turning minimizing carpet fiber twisting. For use on ready-to-assemble furniture, office chairs, printer stands, entertainment centers, and computer desks. U-bracket size is I.D. 11/16". Recommended for use on carpet or ceramic. Load capacity: 40 lb. per caster. 2 per card.