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