This caterpillar toy is so great - it has two sides so they can both play with it at the same time, without having to fight over it. In theory! One side is a bit tricky for them still. But they love playing with the balls that go down the ramp - there are four, two that rattle, two that don't, and apparently banging a rattle ball against a non-rattle ball is the. best. thing. ever.! At least there is one 'set' for each of them!