Ophthalmoscope 3V LED light for examination of fundus..Rheostat on/off switch for adjustment of illumination. Focusing wheel with corrective lenses, illumination 24 colour coated lenses -25 to +40 for excellent resolution (Red for - Green for +) . Adjustable via easy accessible wheel. Rubber brow-rest prevents scratching of eyeglasses. Variable illumination strength via the handle rheostat dials. Lens Selection Disc: Focus on the fundus, cornea, iris and other ocular structures. Easy secure screw fitting mechanism to replace heads Free Extra Bulb Secure bayonet locking system