A scale should always be included when doing one-to-one photography.
Use it with our 1:1 lens adapters.
It is available in white with black printing, the adhesive is non permanent so
the scale may be applied to any surface, including paper, and removed
without damage to the surface.
If you get in the habit of always using a metric scale in your one to-
one photographs, you will always know that each line is a
millimetre. With other scales, the lines may be one-quarter, one eighth,
one-sixteenth, or one-thirty-second of an inch.