English: Sliding vernier caliper BEM brand -12cm steel and brass calipers. Measurement scale on handle. Window on part of tool to see measurement. Marked but illegible, and "BEM" at bottom of handle. A quality sliding gauge, made of steel, with a vernier scale reading up to 120mm by tenths of a millimetre. The vernier system was clever and accurate. On the sliding part of the gauge a section was divided into ten spaces. the first line when read against the main part of the gauge showed the number of full millimetres. Any extra fraction of the millimetre was read by seeing which of the lines of the vernier scale coincided with a line on the main scale. If, for example, it was the 7th line of the vernier scale, that would indicate .7 of a mm, to be added to the number of full mm.