2.7v Ophthalmoscope uses halogen light for true tissue color and consistent, long-lastingillumination. It is versatile and reliable for general use. Halogen light for true tissue color andconsistent, long-lasting illumination. 6 apertures for generalist use: micro, small, and largespot sizes, fixation target, slit aperture, and red-free filter. 24 focusing lenses with a range of -25 to +40 diopters.