The Rainbow River Stones emphasize nature with the flow and randomness to mimic real river stones. There are three different sizes of river stones to suit the needs of growing children and to allow many creative route designs. This activity helps children learn to adapt to the environment through game experiences. It improves self confidence, concentration, and reaction capacity through challenges of the game. It also improves one's action planning ability while activating muscle development. Components: Large (2 pcs.) Diameter 15.79" -Maximum Stone Height 5.12", Medium (2 pcs.) Diameter 13.98" -Maximum Stone Height 5.67", Small (2 pcs.) Diameter 10.94" - Maximum Stone Height 3.43", Maximum Height w/3 Stacked Stones: approx. 11.42". MaximumWeight: 176 lbs. Ages: 3 years & up.