Early version of the No. 540, a retrofit for existing Inverto frames.
Images from Page 3 of the 1949 K&D Tools Catalog. This is the earliest reference for the No. 540 found so far. |
An improved version of the No. 540 from page 20 of the 1961 tools catalog. Note the refined shape and new lever design compared to the earlier version. Introduced prior to 1958. |
The No. 540R from Page 1 of the 1949 K&D Tools Catalog
The version was easily installed by the watchmaker as the required mounting holes were standard features of the 18B/R frame. |
The No. 540S from page 2 the 1986 tools catalog. Note the improved micrometer stop. A satin chromed thimble much like a typical machinist's micrometer. Introduced prior to 1958. |