The M400 Power Bank is designed specifically for use with our M400 Smart Glasses and features the same rail design. Vuzix's unique design enables users to hot-swap out the power bank, meaning you never need to interrupt your work when changing out the battery. This 1000 mAh replacement battery can be worn with all M-Series head mount options. It has a 3 LED power level indicator, and provides 2 to 5 hours of power. Battery state is also displayed in the M400 viewer. IP67 Rated.