Listing is for one (1) Service Caster Series #30 swivel caster with a 4" diameter by 2" wide thermoplastic rubber flat tread on polyolefin core wheel and a bolt on swivel lock capable of supporting 300 lbs./caster. Introducing Service Caster's replacement caster, a perfect alternative to the McMaster Carr caster 30305T561. When searching for a reliable and durable solution for medium and heavy duty projects, consider Service Caster’s Series 30 thermoplastic rubber flat tread on polyolefin core casters. The soft flat tread is made of thermoplastic rubber that is non-marking and non-marring and on the polyolefin core provides a long lasting, high capacity wheel that is capable of easy rolling under heavy loads. Finely crafted with double ball bearing heat treated raceways, these versatile casters are ideal for a wide range of applications, such as dollies, platform trucks, warehouse carts and freight terminals. Or ensure a smooth and secure ride for food service carts, hotel housekeeping carts, and industrial and commercial equipment. Even drywall carts, welding carts, and wall panel carts will be ready to roll on the Series 30, keeping you moving forward. Service Caster is unsurpassed in quality, reliability, and excellent customer service. Count on us to move you forward.