Model # 17148: A proper fitting breast flange can make all the difference between continuing to breastfeed and early weaning. The Ameda Custom Breast Flanges with Inserts should be used when a standard sized flange is too small for comfortable pumping. This product provides mothers with a larger flange and special reducing inserts to create an "in-between" size...larger than our standard HygieniKit Flange, but smaller than the Custom Flange alone: 30.5 mm, reduces to 28.5 mm with insert.