Dimensions This plate mount swiveling caster is approximately 4" in height (including the plate mount. The wheels are approximately 3 1/8" in diameter and the twin wheels are approximate 1 1/2" wide. Please see the Dimensions Illustration for more dimension specifications. Construction The Outer Wheel plate is constructed of steel. The tread is nylon.The Inner Wheel is constructed of ABS plastic. The Wheel Support is Zinc. The color is silver with black tread. Installation Each caster attaches with 4 #10 Pan Head screws. Application These casters were designed for furniture, rolling pedestals, filing cabinets, tables, etc.