Quadralateral Model Kit 8" stainless steel 3 dimensional manipulative projective geometry kit / activity of triangles and quadralaterals. Slides up, down & sideways, transforming triangles and quadralaterals into tetrahedrons. Enlivened in your hands. Comes with instruction sheet of assembly, history and interesting facts about triangles and quadralaterals. Create a manipulative model of triangles, quadralaterals and tetrahedrons!