Features： 1、The electronic display of the handle shows the battery power and the strength of the light source. 2、Toggle the rebound switch, toggle upward, the light source becomes brighter and brighter; As you scroll down, the light decreases in brightness until the power is turned off. 3、Suitable for eye examination, principle of coaxial parallel light, optical glass lens, five different light spots. 4、Diopter range: ?20d ~+20D; Strong reducibility, indicating ≥90%. Stable optical effect, constant current voltage IC built in handle. 5、Low power LED light, service life up to 20,000 hours, long service time. Specification： Item Type: Ophthalmoscope Material: ABS Diopter Range: -20d ~+20D Show: 90% or higher Battery: 2pcs AA batteries (Not included) Principle of coaxial parallel light Optical glass lens, five different spot diopter range: -20d ~+20D LCD screen, handle brightness adjustable reducibility, indicating ≥90% Stable light effect, low power consumption LED light with constant current and voltage regulation built into the handle, with a service life of up to 20,000 hours Package List： 1 x Ophthalmoscope Handle 1 x Ophthalmoscope Lens 1 x Manual