Feature: Comfortable moving more stable and more accurate Optical Engine: Experience smooth and accurate tracking Lightweight, durable design: enjoy the comfort and ease available everywhere Plug and play: Intelligent connectivity, no need to code, plug it into the USB port to get started Fit the palm of your hand shape: the use of natural comfort, reduce hand fatigue. Everywhere you can enjoy comfort and relaxation Note: 1. The hamster mouse needs 1 AA battery (Not included) 2. We have tested it well before sending it out. If there is any question, welcome to contact with us, we would provide the best service for you and help you solve the problem. Thanks!