My 7 year old son goes through drinking cups like theres no tomorrow. He tends to bite as he's drinking from his cup. As a result the tops are only lasting a few weeks - costing me a small fortune. I used to get the tommee tippee, travel cups and order replacement tops in bulk from the manufacturer, but they no longer have that service. I have tried 'fruit shoot' bottles, which only last a few days before being chewed up. Does anyone know of a cup with a strong, durable top that I could purchase. The anyway up cups are quite good, because you can buy replacement tops, but he won't use one.