Caldwell E-Max Pro Battery Pack Feature Caldwell's E-MAX Lithium-Ion Battery is compatible with Caldwell E-MAX Pro hearing protection. Simply charge the battery pack with a micro USB cable and the LED charge indicator will show when the battery is fully charged. With a 16 hour runtime this rechargeable battery pack securely fits in your electronic hearing protection to keep your E-MAX Pros running for a day at the range. Caldwell E-Max Pro Battery Pack Specifications Delivery weight: 4kg Height: 24mm Width: 5mm Length: 44mm