You can do optical experiments by this set of Optical equipment and you can adjust different light with your kids. Feautres: You can use this to do optical experiments, to explore the refraction of light. To help children become interested in physics. Promote the relationship between parents and children. Smooth surface, fine workmanship, harmless, will not hurt hands. It's stored in a protected box. No damage to equipment. Specifications: Material: acrylic Battery: 2 * AAA Water channel: 48 * 30mm / 1.8 * 1.2in Spherical lens: 14 * 6mm / 1.9 * 0.2in Convex lens: 48 * 10mm / 1.8 * 0.4in Concave lens: 18 * 10mm / 0.7 * 0.4in Glass brick: 40 * 12mm / 1.6 * 0.5in 48 * 20 * 10mm / 1.8 * 0.8 * 0.4in Glass plate: 48 * 30 * 2mm / 1.8 * 1.2 * 0.08in Chess: 23mm / 0.9in Biconvex lens: 72 * 35mm / 2.8 * 1.4in Prism: 40 * 35mm / 1.6 * 1.4in Laser-beam generator: 100 * 60mm / 3.9 * 2.4in Package size: 235 * 160 * 50mm / 9.3 * 6.3 * 2.0in Package weight: 435g / 1.0lb Packing List: 1 * Laser-Beam Generator 2 * Glass Brick 3 * Mirror 1 * Biconvex Lens 1 * Water Channel 1 * Prism 2 * Chess 1 * Spherical Lens 1 * Convex Lens 1 * Concave Lens 2 * Battery