KomeStone K4 Quiet Rock Tumbler Kit for Adults, 7LB Large Double-Barrel

• Designed for Adults, Hobbyists, Teens, and Families — The K4 Dual Batch is built for adults and hobbyists who want more than a single-barrel setup, and approachable enough for teens and older children under adult supervision. Whether upgrading from a 3LB kit or a single-barrel machine, the 7LB double-barrel brushless system is the natural next step. Backed by US-based support and replaceable parts.
• At Least 6x Quieter with Safety Cover — Only 50-60dB — The brushless motor and patented noise-reducing cover reduce noise to 50-60dB, at least 6x quieter than non-brushless tumblers without a cover — comparable to a running dishwasher. The cover also prevents curious hands and children from touching the rotating barrel. Unlike most leading dual-barrel brands that leave the barrel exposed, the K4 includes this cover as standard — the safest choice for family environments.
• Tumble Two Batches at Once — 7LB Double-Barrel (3.5 lb × 2) — Two 3.5LB barrels let you run coarse grinding in one while fine-polishing in the other, or process different stone types simultaneously without cross-contamination. No shared environment, no mixing, no cracks. Tumble two batches at once and cut your total processing time in half without extending run cycles — the advantage of dual-barrel over single-barrel tumblers that force you to wait between stages.
• Professional-Grade Brushless Motor for Heavy Loads — Dual-barrel tumbling places higher demands: sustained loads, longer cycles, double the weight. Unlike brushed motors prone to heat and wear, the K4's brushless motor eliminates carbon brush friction — less heat, vibration, and wear over thousands of hours. Rated 40,000+ hours without overheating. When choosing a dual-barrel tumbler, motor type is the difference between lasting and burning out.
• 4-Speed Toggle with Cycle Record, Pause and Memory — 4 speed settings via precision toggle switch, one more than standard 3-speed tumblers, for finer control across stone types and stages. An exclusive cycle record button tracks your current stage, keeping you organized throughout the multi-day process. Program each stage on the LCD with the 9-day timer. Pause to check stones, then resume without losing settings. Auto shutoff and memory recovery after power interruptions.
• Complete Rock Tumbler Kit — Ready to Start on Day One — Includes 1× K4 brushless tumbler, 2× 3.5LB rubber barrels, 2 lbs rough rocks, 8 bags polishing grits (two 4-stage sets: 60/150/600/1200), ceramic media, jewelry fastenings, 3 spare belts, mesh strainer, screwdriver, adaptor, and full-color guide. No additional purchases needed — everything for your first polishing batch is in the box.
• Step-by-Step Guidance and US-Based Support — The full-color guidebook covers setup through finishing your first batch, with polishing techniques, troubleshooting, and practical tips. Our US-based support team is available anytime for questions or machine help. From rough stones to polished treasures — makes a complete geology or STEM gift for enthusiasts of all ages.
• Replaceable Key Parts for Long-Term Ownership — Core components are individually replaceable: motor, control panel, drive belt, rubber barrel, and lid kit available directly from KomeStone with no planned end to supply. The K4 isn't a one-season purchase — it's a permanent part of your hobby setup. KomeStone offers a full lineup from K Series to G Series, with a complete multi-stage grit system.
• 💡We have also prepared extra belts for your spare use at no cost. Reach out to our customer center to get some — absolutely free.
• 𝟗𝟎-𝐃𝐚𝐲 𝐌𝐨𝐧𝐞𝐲-𝐁𝐚𝐜𝐤 𝐆𝐮𝐚𝐫𝐚𝐧𝐭𝐞𝐞 & 𝟏-𝐘𝐞𝐚𝐫 𝐖𝐚𝐫𝐫𝐚𝐧𝐭𝐲 — 𝐑𝐢𝐬𝐤-𝐅𝐫𝐞𝐞 𝐏𝐮𝐫𝐜𝐡𝐚𝐬𝐞 — Shop with complete confidence. Your K4 is backed by a 90-day satisfaction guarantee and a 1-year warranty. Miss Amazon's return window? Our US-based customer service team offers 24/7 hassle-free replacement or refund support — we've got you covered.

7LB Dual-Barrel Capacity – Polishes up to 7 lbs at once, ideal for running coarse and fine grit simultaneously.