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 6240-00-826-1349
NSN 5945-01-631-5431
NSN 6320-01-607-1491
NSN 6645-01-378-1285
NSN 6220-00-967-8382
NSN 5999-01-593-4834
NSN 6145-00-269-4271
NSN 5965-00-275-0491
NSN 5920-00-816-7535
NSN 5910-00-238-9089
NSN 7035-00-360-2008
NSN 5905-01-541-7636