Mice & Trackballs IMPORTANT NOTE This ergonomic mouse is recommended for medium to large hands, as the size of the mouse is 13.7 x 7.4 x 6.8 CM ( 5.4 x 2.9 x 2.7 inch). To get a more comfortable fit and better user experience, we recommend measuring the size of your hand prior to purchasing. Profeional Ergonomic Design With its handy, ergonomic design and high functionality, the vertical mouse is comfortable and supportive for your hand, reducing preure in wrist joint. Comfortable Grip The grip is wider with a gap which makes your hand rest in a more natural way; it doesn't cause as much strain or muscle use to click the buttons. It also has a nice smooth bottom that slides around perfectly on different surfaces.The diamond pattern on the waist surface helps prevent sweaty palms after prolonged use. Browse the web page easily Connect 2 Devices Simultaneously By Bluetooth and 2.4G wirele connection function, can control two devices at the same time, easy to switch1*AA Battery (NOT included) should last 2-3 months or more for most normal users, it will depend on usage Adjustable DPI & Silent Click 3 adjustable DPI (1000/1600/2400) allows you to easily change the cursor sensitivity according to your activity and track more smoothly on various surfaces for general and gaming needs.Gentle and quiet clicking reduces noise without disturbing others and helps you focus on your work. Wide Compatibility Bluetooth mode supports Bluetooth-enabled devices with Windows / Android / Mac OS/ Chrome OS systems.2.4G mode supports all devices with a USB port. It Fits a PC, laptop, cellphone, MacBook, iMac, desktop, or another device.