This item is a set of optical demonstrating model, which is a good tool for teaching. Made of , it is clear and visual to see the . Suitable for better demonstrating the light convergence to students. The product is in a simple design, but it is very useful and practical. Features - ColorBlack - Material: Glass+Plastic+Metal Rod. - Size: 14.50X5.00X2.00 cm/ 5.70X1.97X0.79 inch. - It is made of for durable and practical use. - Intuitive and specific, it is conducted to help students understand and learn. - Can be helpful for students to learn physics formula and the principle of light refraction. - Good for demonstrating optical principles and effects for students, learning about the properties of light. - Can be regarded as a great gift to children who are going to learn the principle of light convergence. Package list: 1 x Concave 1 x Convex