Linen Tester 10X power 35mm Square Metal. A linen tester is a strong magnifier with a built in measuring scale.
Originally the linen tester checks the quality and measure the number of threads within a certain area of fabric.
Today, it measures line width and check the registration of color separations in the field of printing and publishing.
The scale is usually divided into metric millimeters.
Linen testers are also used in other branches of industry.
For example, to measure the line of barcodes, agriculture research and maintenance while spotting microscopic bugs in fruit and maize crops.
This unit has a circle cut in the back instead of solid backing such as M0161