A slide-ruler used to apply scale marks to photomicrographs. There
are four scale lines for producing scale marks of 10 microns,
1 micron, 0.1 micron (100 nm) and 10 nm. The scale marker is also
used in measuring the real life size of an object in a micrograph.
It is made from a clear flexible plastic and it is protected
by an enclosed pouch. Instructions are included. Printed in English,
German, and French.