20pcs Wheel Diffraction Gratings Coated Glass Lens f Laser Stage Lighting

10PCS 5*5mm Wheel Diffraction Gratings Coated Glass Lens f Stage Lighting & DIY& Star lazer pointer ?This laser lens is a diffraction gratings Lens used for as laser stage light, star light Lab, DIY. ?Please keep the lens clean to make the laser beam clear and bright. Before carrying on some laser DIY activities, please read about the technical information first and protect your eyes before laser ray. Be sure the operator has experience in optics DIY or test.