My wife purchase these for my 1 year old, and to me they are just small little cups. Little did I know that these cups are developing my baby's motor control, hand-eye coordinations, and language development. The first couple of times, these cups are just cymbals in my baby's hand. Once the banging durability test is done, she learned the difference between big and small cup and how they fit together. My 3 years old also like these cups. They are a real big hit at her tea parties. When it's all dirty, these cups are dishwasher safe. My family have a lot of spending regrets, but buying these cups almost made up for all of our stupid purchases.