We have been through Soo many cups.my kid got all her teeth in before 6 months, starting with 4 teeth at 1 month old and them popping out 2 at a time thereafter. By 1, she has 24 teeth. She destroyed ever nipple , every silicone top we had. .it bacame quite expensive. Till I discovered these. They last much much longer than any other cup we have tried. Eventually, she will chew a giant hole in the middle of the spout, causing leaking , but it takes about a month versus a few days.See full review