Atman original design grinder, Hummer, the first electric grinder in the world. Compatible with 2 pieces 18650 batteries, to provide enough power to work. Sharp and without cling metal reamer, whic speed reaches more than 130r/min, fast and clean grinder than you ever used. Most important, the device comes with reversal function, so it will never happen to getting stuck. Hummer comes with 4 levels so it can grind the flower into hash completely.