Wheel casters like the 6inch-Lock-Swivel-Caster-004 are used to roll your built machine or equipment back and forth. Diameter of the caster wheel is a metric standard 150mm that is equal to 5.906" inch with imperial units. The thickness of the wheel is 50mm or 1.969" inch. The caster dimensions heightwise is 222mm/8.740" inch. Mounted via a Top Plate that has the size of 140mm x 108mm and the holes distance of 105mm x 75mm. The caster core is made of Polyurethane and Cast iron core and has a Polyurethane and Cast iron core tire with a low friction Ball bearing. Each caster will carry the load of 661 lb and is Swivel and Upper Locking type. Last and not least the temperature range = -40 to 180 F. Remember, you will have to buy the 6inch-Lock-Swivel-Caster-004 in order to have it :).