Pumpin' Pal Super Shields are considerably more comfortable than traditional flanges. Helps users to sit back in a more comfortable, natural position while using most major breastpumps. Promotes better flow & reduces nipple irritation by eliminating constriction of milk ducts while pumping. Customized Sizing: XS & S Pumpin' Pals are pliable silicone ($18.99). M, L, XL are hard Polypropylene ($13.99). Or choose a set of 3 different sizes to assure a good fit for your changing breast size.