The standard sizes of eyepiece graticules used to be 16, 19, and 21 mm. For your convenience, this has been greatly expanded to accommodate a variety of equipment without the need to special order. The following table will assist you in determining appropriate eyepieces for common brands.
Size and Position Scales
Single Lines - NE50
For measurement of large objects in conjunction with a graduated mechanical stage, and for alignment as well. Image covers entire field of view.
||Single Line, nominal width 0.02 mm.
Surface chrome image.