You can do optical experiments by this set of Optical equipment and you can adjust different light with your kids! Have fun! perates with 2x1.5V, AAA batteries(not included in the package). Box Size: 23cmx16cm Quantity: 1 Set Note: Please allow 1-3mm error due to manual measurement. pls make sure you do not mind before you bid Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you! Package Contents: 1 x Laser Beam generator 1 x Triangular prism 1 x convex lens 1 x biconvex lens 2 x square lens(different size) 1 x spherical lens 2 x mirrors 1 x magnifier 1 x water channel 3 x chess 1 x instructions AAAx2 needed (NOT INCLUDED)