Content: 2X 21 mm inserts. Compatible with 24mm Elvie Single/Double Electric, Elvie Stride Cup. It will Reduce 24-mm shield nipple tunnel down to 21 mm. Not original Elvie pump parts. Compatible with Momcozy S9, S10, S12 (24mm Cup)/ Legendairy Milk (24mm Cup)/Tsrete Wearable silicone Cups (24mm Cup). Also compatible with Medela PersonalFit Flex 24mm breastshield, Medela Hands-free Cup(24 mm), Motif Luna 24mm flange, Ameda Mya 24mm flange, Ameda Mya Pro 24mm flange. NOT compatible with 27mm Momcozy M1 Cup. Maintain compatibility with most handsfree bra. You can still use most handsfree bra on the market, having this insert installed inside 24mm detachable shields. Snug fit. Unlike the other version of Maymom longer nipple-tunneled insert, there is no need to trim or cut this model of Maymom insert. Availabe sizes: 21, 19, 17, 15, 13mm. BPA free, made of food-grade silicone. Compliant with US FDA regulations for food contact. Products packaged in retail pack, sealed by manufacturer, Maymom. Maymom newly-designed flange inserts are compatible with Elvie Single/ Double Electric Wearable Smart Breast Pump. Use with Elvie 24mm Cup. Downsize 24mm to 21/19/17/15/13 mm. Sung fit and comfortable to use.