Type bausch and lomb type magnification objective achromatic eye piece 15x diopter adjusting scale -7d to +7d scales corneal radius of curvature 6.4~9.5mm(0.5mm steps) corneal refractive power 52~ 36d(0.25d) axis of corneal estimation 0~180 degree (5 steps) system external reading system illumination 15 w bulb tube head and chin rest adjustable with occluder.