The S2 boasts so many great features and is designed to truly meet the needs of moms wanting to feel confident that they have an effective, powerful breast pump to support supply while also incorporating features to make life a little easier. Like all Spectra pumps, the S2 is a closed system - a physical barrier between the milk and the pump ensures hygiene and motor performance. The S2 is intended to rival the Medela Symphony, and even surpass it with some of its innovative features designed to make life easier for moms. The S2 is hospital grade - strong and efficient enough to support milk supply. With a maximum suction strength of 300mmHg and the ability to be used as a single or double pump. Completely flexible, touch button with the S2 pump's digital controls. These allow you to set the pumping program to the speed and rhythm most effective for your body. The pump will start in 'massage mode', a short, shallow mode designed to stimulate your body's letdown reflex (start the milk flowing) just like how your baby tells your body to start milk flow. The pump will then switch to expression mode, a deeper, slower pattern of suction which mimics how your baby nurses when the milk is flowing. For women who find it hard to get a letdown when pumping, this feature really helps - switch back and forth as needed. The suction is also adjustable whether in let-down or expression mode. Includes a timer and nightlight. This pump is also NEARLY silent... You can see on the picture that you can adjust both cycle (how often the pump 'sucks') and vacuum (the strength of the suction) easily, and the digital display allows you to see your program at a glance. If item has been opened and/or used it is non-returnable due to health and sanitation as these are considered single person use items. For product issues please contact the seller directly and you purchased pump from.