Battery operated - and much to my surprise - it works pretty good! Uses 2 AA batteries, (not included) and comes with two tapered diamond tips. Use for enlarging the holes on pearls, stone beads (hold the bead in a container of water) (it keeps the tip and the bead cool, lubricated, vastly increases the lifespan of the diamond tip, and eliminates dust. You do NOT want to breath in the dust from grinding pearls.) Actually powerful enough to clean out lampwork beads! If the tip gets too wet, it slips, so don't hold too deep in the water. About 5.25 inches long.

By the each.