Begical Flange Inserts 17mm for... https://www.amazon.com/dp/B09KXWCZSC?ref=ppx_pop_mob_ap_share

I ordered these, but any "short" insert should work. I am no longer pumping and in hindsight, I really wasn't a fan of the freestyle flex pump. The cups I loveddddd but not the actual pump. I know My Breast Friend on instagram has shared how to "hack" the cups for other pumps. It's so hard though, because everyone responds so differently. I just have never had much luck with Medela pumps.