4 in. Gray Thermoplastic Rubber and Steel Swivel Threaded Stem Caster with Locking Brake, Capacity 300 lbs, Heavy-duty, Shock absorbent, Durable construction, Smooth rolling, Corrosion resistant, Long-lasting performance, Non-marking tread, Easy installation. 4 in. Gray Thermoplastic Rubber and Steel Swivel Threaded Stem Caster with Locking Brake, Capacity 300 lbs, Heavy-duty, Shock absorbent, Durable construction, Smooth rolling, Corrosion resistant, Long-lasting performance, Non-marking tread, Easy installation. Commonly used on heavy-duty utility carts, mobile workbenches, and storage systems that require frequent movement across large work areas. Well-suited for workshops, warehouses, and industrial-style environments where equipment needs to roll smoothly between stations and then lock securely in place. Also ideal for large DIY builds or custom mobile setups that demand strong, stable support with quiet, controlled mobility on hard indoor surfaces.