NCVI Double Electric Breast Pump has FOUR different modes, and each mode has NINE different levels, which meet most moms' demands. Double pumps to express more milk in less time and single pump for easy to carry, moms can change different sides with no difficulty This breast pump contains a 2200mAh lithium battery, making the pump run two to three times without charge. It can be charged in different ways like computers, power banks, or car adapter. Moms no need to worry too much that machine can not run outside because of no power. This pump contains FOUR flanges of different sizes, moms have more choices, and they are easy to install and uninstall. The TRP silicone at the edge of the flanges is soft, and it will not hurt the breast and prevent the milk leak out. The anti-backflow design is complete, and moms do not need to worries the milk will break the machine. The milk backflow prevention valve prevents the milk flow from the bottle to the body, and the silicone diaphragm prevents milk flow to the pump. The noise value is under 40 dB when the machine runs, which will not wake the babies up at night. All accessories are BPA free which is safe for every mom and baby. NCVI always pays attention to products' safety and practicality, and moms can rest assured to use.