The National Geographic Hobby Rock Tumbler Kit is a complete rock polishing kit that allows your kid to turn rough rocks into gemstones. Tumbler kit by National Geographic includes one pound of rough gemstones, eight packets of polishing grit, a storage pouch, and five jewelry fastenings. The tumbler base and motor are built to last�and the tumbler barrel is designed to be low-noise and leak-proof. It has a built-in timer and automatic shut-off switch too. Now your kids can create beautiful keepsakes from your favorite specimens.�