Bought this for my 8 month old. I stack the cups, and he enjoys knocking them down, mouthing them, banging them together etc. and in due course he'll be able to stack them himself, use them in a sandpit, in the bath. He could use them in the bath now, but he tends to drink the bathwater, and that's not so good! They are nice bright, solid cups, and having different shapes on the base and raised patterns on the rims gives them another dimension. Being Tolo, they are excellent quality. They are not too large, therefore easy to transport for play at other people's houses, popping in your bag or suitcase, etc.