Description This item is made of premium polished glass with ground edges. They have optically polished faces and ground edges with double convex, it is great for you to demonstrate optical principles and effects. They can provide students with a wealth of opportunities for light and optics experiments. It is also a great choice to assist your children with their science. Feature - Color: As shown in the picture. - Material: Acrylic. - Size: 5 * 5 * 1 cm / 1.97 * 1.97 * 0.39 inch (L * W * H). - Focal length: 50mm. - Diameter: 50mm. - Double-convex (bi-convex) lens for demonstrating optical principles and effects. - Two outwardly curved surfaces converge light rays to a point. - for a variety of light and optics experiments. - Great choice to assist your children with their science.Packing list: 1 * Scientific Polished Glass Double-Convex Lens Labs Optical Glass Lens Bi-Convex 55mm Diameter