? The Fisher-Price Rock-a-Stack toy is classic, colourful fun for your little one! Younger babies will love grasping, holding, shaking & exploring the five colourful rings. The littlest ring has a shiny, reflective surface for baby to discover inside-with colourful, swirling beads that make fun rattle sounds! When they're ready to sit & stack, babies can place the rings on the post, then bat at the wobbly base to make it rock back & forth. Stacking helps them develop h&-eye coordination & introduces them to the concept of relative size as they learn to sort & stack from biggest to smallest!