Listing is for a set of four (4) Service Caster Series #KP30 casters, two (2) swivel and two (2) rigid casters, with 4" diameter by 2" wide thermoplastic rubber flat tread wheels capable of supporting a total weight of 1,200 lbs. (300 lbs./caster). When searching for a reliable and durable solution to your caster needs, consider Service Caster’s Series KP30 thermoplastic rubber on polyolefin core flat tread 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. Featuring a Kingpinless hot forged ASTM1045 steel design that increases caster durability and integrity, the series KP30 eliminates problems associated with kingpin failure due to severe shock loading. In addition, the Kingpinless design features 3/8” diameter HRC45 steel ball bearings which absorb thrust and load in severe environments. Lastly, Service Caster’s Series KP30 casters are finely crafted with grease fittings, and 4 position notches to accept 4-position locks. These highly versatile casters are ideal for a wide range of applications, such as dollies, platform trucks, warehouse carts and freight terminals. Even drywall carts, welding carts, and wall panel carts will be ready to roll on the Series KP30, keeping you moving forward.