Features variable voltage, allowing you to control how large of a sip you take. With a slim profile and a long-lasting 350 mAh rechargeable battery. These batteries feature variable voltage, allowing you to control how large of a sip you take. With a slim profile and a long-lasting 350 mAh rechargeable battery, this battery can be easily slipped into your pocket or bag for a weekend at the cottage or lounging on the beach.