The Medela Advanced Pump In Style Battery Pack can only be used with the Medela Advanced Pump In Style made 2003 - 2007. It is not interchangeable with the Battery Pack for the Pump In Style Professional Model or Traveler Breast Pumps. It uses 10AA alkaline or rechargeable batteries to provide up to 3 hours of pump use. 15V DC 2A. The black microfiber carrying case is not included with the Battery Pack.