Many women prefer manual cycling because it gives them more control over the pumping process. You can change the cycle time as you are pumping to mimic the way your baby nurses and maximize your pumping efficiency. To create suction and cycle the Nurture III, you cover and uncover a vent on one of the collection bottles with your finger or thumb. It's a very small, easy motion and you only do it on one side, even when you're double pumping. The Nurture III reaches 220 mm Hg (the natural suction level of babies) in 2-3 seconds, allowing you to cycle it 20-30+ times per minute and enabling you to express both breasts in 10-20 minutes.