Five colorful rings are fun for younger babies to grasp, hold, shake and explore. The smallest ring features a shiny, reflective surface for baby to discover inside with colorful, swirling beads that make fun rattle sounds. When baby is ready to sit and stack, baby can place rings on the post and then bat at the wobbly base to make it rock back and forth. Stacking helps baby develop eye-hand coordination and introduces baby to the concept of relative size as they learn to sort and stack from biggest to smallest. Rock-A-Stack is recommended for children ages 6 to 36 months.