Features:The Welch Allyn AutoStep Coaxial Ophthalmoscope uses a Halogen HPX lamp that provides 30% more light output, for true tissue color and consistent, long-lasting illumination.Its 68 lenses in one diopter steps provide better resolution.It has 6 apertures for general and specialist use.Its rubber brow rest prevents scratching of eyeglasses.Its illuminated lens dial clearly identifies settings.Product Information:Additional Features Include: The coaxial optical system produces shadow-free spot and easier entry into undilated pupils. The crossed-linear polarizing filter reduces corneal reflection. The red-free filter may be used with any aperture. The 18 possible aperture combinations provide greater versatility, and the sealed optics provide better dust protection. The Welch Allyn 11730 3.5v AutoStep Coaxial Ophthalmoscope (Head Only) Model 11730 uses patented coaxial optics, Halogen HPX illumination, and 68 focusing lenses combine for premium quality. Key Components 3.5v AutoSt