The Spectra Simple Store Milk Collection Replacement Milk Bags are meant to be used in conjunction with the Simple Store bottle connector which allows moms to pump, store and feed babies breastmilk all in one simple product! This NEW system is convenient for busy moms and prevents the exposure of germs and outside contaminants that are often present when transferring milk from one storage solution to the next. All Spectra Simple Store Milk Collection Replacement Milk Bags are double lined and provide a strong seal ensuring leak-free insulation moms can count on. Assembly is intuitive, clean, fast and easy—making it a must for mom and baby!