Microfix Vernier Dial

"Microfix" Vernier Dial
With most modern sets, especially those employing a stage or two of H.F. amplification, fine tuning dials for the variables are almost essential if the condensers themselves are not fitted with “vernier" movements.
Of the many fine tuning dials on the market now the new Microfix," due to Messrs. Harlie Bros., 36, Wilton Road, Dalston, London, E.8, stands out as being of rather more than usual interest. In the first place it costs but 5s. 9d., which is a reasonable figure for such an article.
Then again, the construction and design of this Harlie product are both of the highest class. Practically no metal at all is used in this dial, and the movement is quite velvety. The gearing has a ratio of 1 to 120, and provision is made for the usual direct drive. The dial measures a full four inches in diameter and has a large control knob with which the fine adjustments are carried out. This latter has its own clear indication markings.
Modern Wireless May 1927, Page 542

Here you find 8 models, 6 with images and 0 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
All listed radios etc. from Harlie Bros.Ltd., London