A graduated scale, usually cylindrical in shape, attached to, or forming a part of, the focusing nut or knob of the eyepiece of an optical instrument. It is read in conjunction with a line or dart indicator to measure the change in refracting power of the eyepiece, in diopters, and introduces correction to compensate for the eyesight variation of the observer. It may have a knurled periphery and/or teeth on the inside diameter.
Classification: Military equipments not identified by kind
NSN 5895-00-868-9974
NSN 6320-01-352-5653
NSN 5920-01-123-9854
NSN 5930-01-194-1874
NSN 5996-00-137-2684
NSN 5905-01-197-7929
NSN 5999-00-991-0840
NSN 5935-01-005-1757
NSN 5895-01-228-2996
NSN 5975-01-533-1874
NSN 5915-00-409-0168
NSN 6105-01-361-3270