This portable set features Welch Allyn's finest diagnostic instruments. The Coaxial Ophthalmoscope (11720) uses a Halogen HPX lamp that provides 30% more light output for true tissue color and consistent, long-lasting illumination. It has 28 lenses from -25 to diopters for better resolution. The coaxial optical system produces a 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. It has 18 possible aperture combinations for greater versatility. The Welch Allyn 3.5V Operating Otoscope Head with Specula (21700) has an open system, rotatable lens and speculum for convenient procedures. It uses a Halogen HPX lamp that provides 30% more light output for true tissue color and consistent, long-lasting illumination. The fiber optic illumination produces cool light. It has a rotatable lens and speculum. The 71000A universal rechargeable handle accepts all Welch Allyn 3.5v instrument heads. Its chrome-plated brass handle rests comfortably in the hand. It comes with an adjustable rheostat control; smooth, knurled finish; and safety switch to prevent accidental battery drainage. It can be recharged by plugging directly into a wall outlet.