These are some physics optical lens applied to understand the principle of light convergence more intuitively. Adopting , they are safe and for long period to use. Small size, easy to use, these physics teaching lens can stimulate students' cognitive ability in physics, giving you more convenience. Features -Color:White -Material:Glass -Size:6.00X3.00X1.00cm/2.36X1.18X0.39in - Made from premium glass materials, these optical lens are professional and for long period to use. - With different shape, practical convex and concave lens can effectively explain the knowledge of optics with experiments - Science teaching tools can stimulate students' cognitive ability in physics, also can be a good helper in school teaching - Good tool to show how different aspects of lenses and light passing through and bending, of multiple uses - Easy to use and clean, save your time and efforts to let you have satisfying using feeling Package list: 7 x optical lens