400 Series, 4", Thermoplastic Rubber, Swivel Plate Caster With Brake, 250 LB Load Capacity, Plate Size Of Holes 1-3/4-Inch x 2.90", Gray Thermoplastic Rubber Treads On Black Polypropylene Hubs, Offers A Soft Cushioned Ride & Are Quiet, Excellent Flat Spot Resistance & Is ResistAntique To A Broad Range Of Chemicals, Acids, Solvents & Detergents, Non-Marking, Performs Well In Wet & Corrosive Conditions, Very Good Floor Protection & Impa-Count Resistance, Temperature Range 180&degree. Fahrenheit To -40&degree. Fahrenheit, Durometer 80a + -5, Bulk.