These are honestly the best breast milk storage bags ive used. Super simple, nice quality and awesome strength. The double zip on the bag is super secure and these freeze flatter than others. As well as are accurate to the ounces in the bag where as most are not at all. Great bags. I ordered 200 of them. Will probably need more. I exclusively pump and my milk goes from my breast pump bottles into these bags dated and timed for each pump with amount and then stored in the fridge until used. As well as frozen from time to time.