This is a wonderful sensory puzzle that is achievable to solve from 4 years and up. Move the inner balls, (in a slide fashion), across to the empty space, to manipulate the colours, so that they all eventually match up.
You can only move the balls closest to the 'hole,' so it takes focus to work out where to move each ball so that you can match the colour ball to the same colour hole.
A great one for in the car that is NON tech in nature.
If dropped on a hard surface sometimes the plastic colour surrounds can come off and generally can be easily clipped back in (unless broken).
Not suitable for children under 3 years of age.