The HealnHealthy Direct Ophthalmoscopes are crafted with an aluminum frame, allowing for shock resistance and eliminating misalignment. Optical components remain clear and precise with no maintenance due to the dustproof design. It illumination allows for around maximum working hours with no need to ever replace a bulb. The LED Ophthalmoscope is comprised of lenses (ranging from -20D to +20D). No pinhole macula aperture. Recessed windows prevent stray light escaping to minimize distractions. One-Handed control for ease of use. Able to examine small and undilated pupils.