It adds strength to your wrist with a simple mechanical function, more leverage thanks to the lengthened handle. The serrated edge assures a tight grip. It’s an essential kitchen tool, and the price is right. There are any number of similar tools that perform the same function, and all work on the same principle, adding leverage with the lengthier handle, which greatly increases torque. Some add a clamp to the jaw as an aid to tighten the grip and prevent slippage. The various versions of the jar opener have a price range but the less expensive work as well as the higher priced ones.