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 5950-01-379-7016
NSN 6620-00-764-6626
NSN 6105-01-171-9163
NSN 5945-01-169-7569
NSN 5945-01-411-7037
NSN 5915-00-932-3040
NSN 5975-00-693-2531
NSN 6105-00-795-7384
NSN 5990-01-351-4621
NSN 6650-00-238-1199
NSN 5905-01-561-0983
NSN 5930-01-142-8729