Double Lens Linen Tester – 1″x1″

More recently they are used extensively in the print trade and photography, to test the quality of the paper and the pixels respectively. A Linen Tester is also the most useful type of Magnifier for looking at watermarks, stamp perforations etc. While there are some cheap plastic models available which are adequate, these  Japanese made, metal models are far superior and the hinge mechanism should not wear out, whereas the plastic ones are likely to break after a length of usage.

Known also as Stitch Counters and Linen Checkers, Linen Testers, as the name suggests, were first introduced to assist in the textile trade.