The Weston Master II was produced in this variant for cine use, in 1946. The dial is calibrated in Relative Brightness and the calculator is used to turn this into the camera f stop setting. Film speed is in Weston and the camera shutter speed can be varied from 6 to 96 frames per second – although 24 was the norm for professional work. This meter was manufactured in Enfield, Middlesex.
More can be read about Edward Weston, the meter, and the company, at: