Ameda CustomFit Breast Flanges Without BPA are designed to provide a more comfortable and efficient pumping for moms who need a larger breast flange. These BPA-free polypropylene flanges are available in available in medium and large. The diameter of the nipple tunnel is 36.0 mm. With the inserts in place, the tunnel diameters measure 32.5 mm. Ameda CustomFit Breast Flanges Without BPA replaces the standard breast flange in all Ameda HygieniKit Milk Collection Systems and Ameda breast pumps.