It has an in-built Rechargeable Li-ion battery and does not require any external battery. Once the battery drains you can plug the type C charging cable provided to charge it (60 mins). To save power and for long-term usage, the mouse will automatically enter into the sleep mode after 11 minutes of inactivity, it can be woken up by clicking any button.Silent click Mouse with anti-fingerprint finish offers you’re the most premium feel. Silent button reduces 90% noises, which makes it an ideal wireless mouse for office and personal use. Symmetric and ergonomic design makes this mouse fit for both left and right hand, naturally curved grip of the mouse makes it comfortable and perfect, avoids hand fatigue for long term use. Slim and portable design makes the mouse your best travel companion.