Dr. Cool Rock TumblerThis hobby rock tumbling kit includes a tumbler and barrel, half pound of gemstones (9 different types), polishing grit (4 grades), jewelry fastenings, learning guide and instructions. The metal base and high powered motor give you a workhorse machine that will last for years. Features a noise reducing rubber barrel with stainless steel lid that is both leak proof and much quieter than plastic barrels. This easy to use tumbler has a programmable