Professional Opthalmoscope Halogen light for true tissue color and consistent, long-lasting illumination. Apertures: large and small spot,semicircle, and red-free filter, Correcting lenses range: +in 1D steps |1-4|6|8|10|15|20|0 & -in 1D steps |1-4|6|8|10|15|20 Bulb:2.5V 1.6W Halogen Lamp....