Polydron Boxes Contain A Mixture Of Original Polydron And Frameworks Pieces All Housed In A Handy Storage box. Both Systems Are Compatible With Each Other. Polydron Contains Unique Joints Which Readily Snap Together Giving A Superior Hinge. They Are A Leading Resource In Schools Around The World For Teaching 2D And 3D Shapes In Geometry. Build Over 60 Models With This Set. Contains 126 Pieces: 2 Swivel Joints, 12 Right Angle Triangles, 22 Squares, 84 Equilateral Triangles, 6 Isosceles Triangles, Guide And A Tub. Age: 4+.