Just tried these bottles and I am so glad I did! My son was nursed and when we used bottles they were the avent ones. I tried starting him on sippy cups at 9 months and he wouldnt even touch them. He cried when he saw one. Even the ones made by avent that simply are interchangeable from nipple/spout using the same bottle base. At 12 months his pedi warned me he really needed to be off the bottle. Knowing she would see him in another three months I bought a sippy almost every week and gave it a solid try for week. I know have 14 different sippy cups stashed in the very tops of my cabinets. Finally at 14 MONTHS he is off the bottle! He loves the handles on these he carried it around instantly. After 30 minutes of playing with it he was drinking from it like a champ. No more bottles just in time for his pedi too. These bottles are cute and easy to clean. I love that the handles are so easy to put on ,unlike others that require you to line them up with the spout. Plus it seems hard to find a sippy that still has measurments on the side. Have not had any problems with leaks yet. Some of the other sippys I tried leaked just when shaking them while mixing a drink or laying on it's side. He has several teeth and has yet to bite through this spout. Also they sell replacement spouts. Highly recommend to anyone who is having similar problems. The only thing I dont care for about this product is the price and not all stores carry them.