Early Learning Duck Rainbow Stackers Colorful Rock-a-stack Classic Sensory Baby Educational Toy Gift Different bright colors stimulate visual development.Placing rings on the pole strengthens eye-hand coordination. Two-in-one toy ,rattling yellow duck and rainbow stacker, arouse baby's curiosity. Product size: about 11.41*5.51(the bottom stacker diameter) Helps baby learn to distinguish colors and sizes of rings. Hands-on activities strengthen baby's motor skill and problem solving skill.