Maymom Flange Inserts for Freemie Cup are funnel-shaped silicone flange inserts for Freemie Collection Cups.Maymom inserts to reduce nipple size of Freemie cups to 21 mm, all the more comfortable for nursing mothers with smaller nipple diameters.Made by Maymom for Freemie. Always choose a flange nipple size 1-3 mm more than your after-pumping nipple size Reduces the flange nipple size diameter to suit you Fits both open and closed system Freemie Collection Cup Made from Silicone and PP – BPA free, and DEHP free You must “fold” the insert to install, and “twist and turn” to remove the insert. If you don’t do so, it is hard to install and remove.See instructions that come with the product. For flange insert size 17 mm, 19 mm, fits inside 25 mm Freemie flange For flange insert size 21 mm, fits inside 25 mm & 28 mm Product contains 2 xMaymom Flange Inserts for Freemie Cups. How to fit the insert: Simply seat the flange insert inside the flange. Cleaning Place the insert in boiling water for 5 minutes before first use. Clean in soapy water, and rinse with clean water, then air dry after each use.