Specification includes a light source (LED, Fiber Optic), a handle W/ C Size 1.5Volt × 2 batteries-powered, with rotary switch), and a head with interchangeable components like specula (for otoscopes) or diopter wheels (for ophthalmoscopes). Magnification, with otoscopes commonly offering 2.5x to 4x magnification and ophthalmoscopes using diopter correction lenses from –25 to +40 for examining the eyes.