Covington's Rolling Tumblers are stout American-made machines built to last. Our Rolling Tumblers feature a solid EVA barrel. These quiet running units utilize raised ridges inside the barrel which prevent sliding and promote a faster grind. The proper rotary speed is preset in factory to ensure maximum abrasion and polishing action.Units are powder coated for durability and longevity. The steel support shafts are cushioned by nylon bearings. The barrel rests on the steel supports and lifts off for easy inspection and cleaning. The steel support shafts are cushioned by nylon bearings and are supported in the middle to ensure that the shafts do not bend from the weight of the barrels. The barrels rest on the steel shafts. This unit ships complete with a small sample of Old Miser, instructions, and a product guarantee.