Hi Caitlin88--- The 21mm Breast Shield replaces the standard 24mm Breast Shield that comes with our breast pumps and has a narrower opening and shorter tunnel. The 21mm Insert is used in conjunction with our 24mm Breast Shield. It is inserted into the 24mm Breast Shield in order to help make the opening more narrow, but keeps the length of the tunnel. Some moms who find that their nipples need a narrower opening, but still need the longer tunnel length, benefit from using the insert. Please feel free to reach out to our team if you need further assistance. We're here to help!
Date published: 2018-07-02