KoolStone is a rock tumbler brand aimed at hobbyists who tumble at home, selling mainly through Amazon in the US and through its own shop. The range is one family grown step by step: the C1, then the C1 Pro, C1 Pro Max and the current C1 Pro Ultra with a dual drum layout. The company built its pitch on being first to put a brushless motor in a consumer tumbler, and on rubber barrels it says cut noise by about 75 percent against plastic ones. Controls are generous for the price: three or four speeds, a nine day timer with auto shutoff and memory, and a cycle record button.
Kits arrive complete, with rough gemstones in nine varieties, spare belts, several grits, ceramic media, a sifter and jewelry fastenings. Warranty is one year with a 90 day trial, and support runs by email. Buyers who want a machine they can still rebuild in ten years will feel safer with the old American shops.
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