The Medela Swing was designed for moms on the go! It easily fits into a purse or briefcase and is mobile enough to use on a tabletop, with the belt clip or with the included shoulder strap. Two different modes help simulate a baby's natural nursing patterns and help provide maximum milk flow: Let-down Mode initiates faster milk flow and Expression Mode provides maximum milk flow. SoftFit? Breastshield makes it plenty comfortable, and it can be operated with its electric adapter or 4 AA batteries