Full Featured pocket ophthalmoscope set that sacrifice nothing but size. Pocket clip with integral on/off switch for ambidextrous use. Ophthalmoscope head features a 2.5v halogen lightsource for true tissue color. 5 Aperture selections (small, large, fixation, semicircle and red-free). 17 lenses from minus 20 to plus 20 diopters. Illumimated dial. Silocon coated protection of glass compoants. Built in lens dust cover. Ophthalmoscope head made from polimid, an impact reistant thermoplastic. Lifetime Quality Performance Guarantee on Optics