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 2925-01-146-0278
NSN 6135-01-576-9616
NSN 5985-01-069-8566
NSN 5945-00-073-6384
NSN 5915-00-145-4936
NSN 4140-00-513-1089
NSN 6650-01-549-8478
NSN 5855-00-256-5562
NSN 6620-01-007-4249
NSN 5960-00-906-6087
NSN 5925-01-209-2768
NSN 6320-01-185-3857