Ergonomic Design: The mouse has an ergonomic design for comfortable use USB Connectivity: The mouse is connected via USB Receiver for easy use 3 Button Functionality: The mouse has 3 buttons for various functions Battery Powered: The mouse is powered by batteries for portability Lekvey Only: Lekvey 2.4GHz USB Receiver for Standard Wireless Ergonomic Mouse ( Brand only, Not for M550, M550 Pro Series )