POLYURETHANE TREAD: Heavy duty caster is made of a polyurethane tread on polyolefin core for long life and keep all floors clean and free of tread marks. The combination of flat tread and high-quality polyurethane can withstand heavy loads and frequent use. INDUSTRIAL CASTER SIZE: Caster size diameter: 4 inch, width: 2 inch, Hub Length: 2-7/16 inch,with ¾" roller bearing. Top plate: 4x 4-1/2 inch, total height: 5-5/8 inch. Polyurethane wheels have excellent floor protection and easy rolling properties. HEAVY DUTY LOAD: Industrial casters are made of high-quality polyurethane and galvanized thickened yoke, with strong load-bearing capacity. The sturdy material allows you to move heavy loads with ease and safety. Each caster holds a maximum of 700 lbs.(Sets of 4 load 2800lbs) NO-MARKING & SMOOTH: Outdoor caster wheels design with roller bearings, these wheels guarantee durability, longevity, and superior roll-ability. Mark-free gliding experience on a variety of floors. WIDE APPLICATION: Polyurethane caster wheels heavy duty are suitable for both indoor and outdoor applications, mainly used in Hospitals, warehouse, Bakeries, Schools, Laboratories, Animal Labs, Clinics, and many institutional applications. NINOSO Caster Wheels, 4" Industrial Heavy Duty Casters, Polyurethane Tread on Polypropylene Core, Casters Set of 2 with Load 1400lbs Capacity, Wheels for Cart Toolbox Equipment (2 Rigid)