The Pump In Style® with MaxFlow™ and Pump in Style® Advanced Battery Pack makes pumping on-the-go or when you are not near a power outlet easy and convenient. In the car, at work, or at home; you've got up to 2 hours of pumping time. The battery pack uses 8 AA alkaline or rechargeable batteries and comes with a black microfiber carrying case, which fits inside your breast pump bag or can be attached to the bag strap for easy transportation.