• For use with the Medela Pump In Style (sold separately)
• Uses eight AA batteries
• Provides approximately three hours of pumping time (ten to 12 pumping sessions)

What could make the Pump In Style even better? Medela's Pump In Style Battery Pack, which you can use to express milk anywhere, even if you aren't near an electrical outlet. The pack uses eight AA batteries and lets you pump for ten to 12 sessions (approximately three hours). It fits either inside or on the shoulder strap of the Pump In Style carrying case for easy access.