So, I bought these bags as an alternative to standard milk storage bags, as you can attach them to the pump. This removes the need for sterilising bottles in addition to using bags. They attach easily to the Medela Swing pump (I see no reason why they wouldn’t attach to other pumps too). However, you can only use the attachment once so, if you want to top up the bag later in the day, you have to use a bottle anyway. Fantastic, and time saving if you don’t need to top up. They are great quality bags though, don’t seem to have much chance of leaking or splitting like the cheaper brands do.
HC, Feb 2011