You can"t beat Medela for quality, and you can"t beat a backpack for portability! Only Medela uses a research-based, 2-Phase Expression(R) technology that simulates babies" actual nursing pattern. This sporty, compact backpack holds Medela"s hospital-grade, double breast pump, plus everything you"ll need for quick, comfortable pumping. Includes AC adapter, or use with 8 "AA" batteries (sold separately). Only Medela pumps use research-based technology that replicates baby"s natural sucking patterns: a faster Stimulation Mode, followed by a deeper, slower Expression Mode. The pump switches modes automatically, or you can control it yourself with the press of a button. With one adjustment, you can set the pumping speed/vacuum intensity for comfortable, personalized double or single pumping Includes everything you"ll need, including: Quiet, built-in 9-volt motor Removable cooler with ice pack for up to 12-hour milk storage Four 5 oz. self-standing, Bisphenol-A free bottles with lids. (Bottles remain self-standing, even with pump attached). Soft, PersonalFit breast shields Soft-cover battery pack (8 "AA" batteries sold separately) In a sporty, hands-free backpack Compatible with Medela"s 9-Volt Vehicle Lighter Adapter (sold separately) Clean pump parts easily with our QuickClean microwavable steam bags (sold separately)