Portable 2.4Ghz Wireless Optical Wheel Mouse Mice w/ USB Receiver for PC Laptop Blue Automatic Power off (APO) Powered by 1 x AAA battery.(NOT included) On/Off switch maximizes battery life. Ergonomic Design accomplish comfortable experience and accurate operation. Size:9.7cm x 6cm x 3.4cm-3.81inch x 2.36inch x 1.33inch.