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 Many Questions about Services Are As Follows: 1.How many orders can you handle per day? we are a large company in Shenzhen,China,with a large warehouse that can handle large orders everyday.We send out countless parcels everyday.We can guarantee the order you request. 2.How fast can you process orders? We will arrange shipment as soon as possible after you pay the order.Priority delivery for order 3.Could you ship order without any receipts,invoices and promotional offer inside the package? Absolutely!No invoices,receipts,promotional offer if you leave notes on the order(if you want,we can provide.) 4.If you need other products? We can provide most products you need as much as possible1 If you have any other questions,please feel free to contact us. We are very grateful to cooperate with you. 5.We can support CSV/Excel File . 6.There is no limited stock to fulfill the orders on a daily basis