Fisher-Price Rock-a-Stack Baby Activity Toy provides lots of fun for little ones. Younger babies will love grasping, holding, shaking and exploring the 5 colourful rings. The littlest ring has a shiny, reflective surface for baby to discover colourful, swirling beads that make fun rattle sounds. When they're ready to sit and stack, babies can place the rings on the post and bat at the wobbly base to make it rock back and forth. This Fisher-Price Rock-a-Stack Baby is a great sensory toy. Stacking helps them develop hand-eye coordination and introduces them to the concept of relative size, as they learn to sort and stack from biggest to smallest.