Welch Allyn's Auto Step Ophthalmoscope features 68 lenses ( -30D to +38D in automatic one diopter steps), coaxial optics and HPX halogen illumination. The Welch Allyn 11730 Ophthalmoscope includes 5 standard apertures, plus cobalt blue filter, separate crossed linear polarization filter, and separate red-free filter. Use the independent filter switch in conjuction with the standard aperture wheel for up to 18 aperture/filter combinations. The 3.5 volt AutoStep Ophthalmoscope uses the 04900
halogen bulb, and runs on all Welch Allyn 3.5v power handles.