Welch Allyn Diagnostic Ophthalmoscope Set Ref No. 11720- with Original Welch Allyn Dry Handle in Case DESCRIPTION Welch Allyn 3.5v Halogen Coaxial Ophthalmoscope Head #11720 and Dry Battery Handle in case. The patented Welch Allyn Coaxial Vision System facilitates ophthalmology by enabling easier entry into the eye, a larger field of view, and reduced glare compared to standard Ophthalmoscopes. Features: Halogen HPX lamp provides light for true tissue color and long-lasting performanceCoaxial optics produce a shadow-free spot, easier entry into undilated pupils, and a larger field of view versus standard ophthalmoscopesDetect corneal abrasions with cobalt blue filterPolarizing filter virtually eliminates corneal reflectionSealed optics keep out dust and dirt18 unique aperture/filter combinations for greater versatilityRed-free filter may be used with any aperture28 focusing lenses with a range of -25 to +40 diopters