National Geographic Professional Rock Tumbler Kit- Advanced Features Include Shutoff Timer & Speed Control - 2Lb Barrel, 1Lb Gemstones, 4 Polishing Grits, Jewelry Fastenings & Learning Guide Create stunning gems - transform ordinary rocks into beautifully polished gemstones with this professional rock tumbling machine from National Geographic A complete hobby kit - includes our Pro series tumbler, 1lb of rough gemstones, four polishing grits, jewelry fastenings, information guide, and instructions Built to Last - this powerhouse machine will last for years and features a 2lb leak-proof rubber barrel which makes less noise than other tumblers Professional features - includes a speed control and shutoff timer for faster tumbling times and better polishing results Respected quality - this premium tumbler comes with National Geographics 100% satisfaction guarantee and a 2-year warranty