2 years & up. The Rive Stones are designed to improve coordination and balance. Jumping or stepping from stone to stone developes a child's confidence in their ability to judge distances. The side of each triangular block varies in steepness and difficulty, and the layout can be changed to make a pathwat more or less challenging. Each stone has a non-slip rubber rim, which also protects indoor surfaces. River Stones can be conveniently stacked for storage. Each set includes 6 stones in 6 colors: three measuring 14.96" x 14.56" x 3.35" and three measuring 10.23" x 10.23" x 1.77".