Superball Caster, 2" Dia Vinyl Wheel, W Stem, Soft Tread, Bright Brass, 4/Set MAS53516 Decorative, hooded ball caster 2-inch diameter soft vinyl wheel can be used on low-pile carpeting, chair mats and all hard floor surfaces Weight rating 75 lbs per caster W Stem - for chair bases with 5/16-inch diameter wide opening for stem, up to 1-1/2-inch deep