The Fisher-Price Rock-a-Stack toy offers classic stacking fun for your baby. 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 theyre ready to sit and play, babies can stack 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!