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 6240-00-194-3304
NSN 5945-00-112-9142
NSN 6220-01-012-2191
NSN 7035-01-600-6139
NSN 5930-01-067-9131
NSN 5996-00-386-2236
NSN 5965-00-035-4556
NSN 6685-01-473-8713
NSN 7035-00-902-8995
NSN 6105-01-139-3624
NSN 5905-00-539-3533
NSN 5965-01-512-3811