Mine were “LuvMy” brand on Amazon. They don’t always have them (I checked just now and they don’t, so I can’t link to you!). But I’ve heard good things about Nora’s Nursery, and they look to be a similar price at $2.50 an insert. Bamboo is great and I’d have enough to eventually use 2 at a time if you have a heavy wetter like I did!

Bamboo Inserts https://www.amazon.com/dp/B017WYJEA8/ref=cm_sw_r_cp_api_glc_fabc_Uco3Fb52SV97K