Custom-designed 860 mAh battery is compact and balances M300XL Smart Glasses on all Vuzix frames. Includes a micro USB charging port, on/off switch, three power indicator LED lights, and a USB socket for use with an optional Wi-Fi dongle. This replacement battery provides 2 to 5 hours of power and is hot-swappable for continued all-day use of M300XL Smart Glasses.