Features: Crystal prisms with safe rounded edges are ideal for teaching students about the nature of light and how to create rainbows, making learning fun. 4 Inch triangular prism is an ideal science experiment and classroom learning supplies, shooting props, party gifts, etc., to meet the needs of learning and playing. Specifications: Material: crystal glass Color: clear Size: about 4 inch Package includes: 12 pieces Notes: Manual measurement, please allow slight errors on size