?The Fisher-Price® Rock-a-Stack® toy is classic, colorful fun for your little one! Younger babies will love grasping, holding, shaking and exploring the five colorful rings. The littlest ring has a shiny, reflective surface for baby to discover insidewith colorful, swirling beads that make fun rattle sounds! When they're ready to sit and stack, babies can place the rings on the post, then bat at the wobbly base to make it rock back and forth. 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!?