MX-2118 3D Wireless USB Optical Mouse [MS-21-18-WC] is the state-of-art professional Small Wireless Mouse. With the Ergonomic design, MX-2118 is designed to be comfortable and specially fit for your hand position and avoid fatigue after use it for long period. Tranquil-design wheel for scrolling four contact points to reduce resistance and ensure excellent mobility and easy to control on different surfaces. MX-2118 is using AAA battery. Specially, the USB receiver can plug inside the mouse. Very easy to carry.