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 x AAA Water channel: 48 x 30mm or 1.8 x 1.2in Spherical lens: 14 x 6mm or 1.9 x 0.2in Convex lens: 48 x 10mm or 1.8 x 0.4in Concave lens: 18 x 10mm or 0.7 x 0.4in Glass brick: 40 x 12mm or 1.6 x 0.5in 48 x 20 x 10mm or 1.8 x 0.8 x 0.4in Glass plate: 48 x 30 x 2mm or 1.8 x 1.2 x 0.08in Chess: 23mm or 0.9in Biconvex lens: 72 x 35mm or 2.8 x 1.4in Prism: 40 x 35mm or 1.6 x 1.4in Laser-beam generator: 100 x 60mm or 3.9 x 2.4in Package size: 235 x 160 x 50mm or 9.3 x 6.3 x 2.0in Package weight: 435g or 1.0lb Packing List: 1 x Laser-Beam Generator 2 x Glass Brick 3 x Mirror 1 x Biconvex Lens 1 x Water Channel 1 x Prism 2 x Chess 1 x Spherical Lens 1 x Convex Lens 1 x Concave Lens 2 x Battery Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.