• they are square, with a size of 2-1/4 inches by 2-1/4 inches
• they are made of metal
• they have a circular cut-out so that the timepiece is set into the plate
• they have two sets of holes -- a set of three small holes to attach the timepiece to the plate and a set of holes to attach the back-plate to the dashboard

Having now described the common specifications, scroll to the text below the photographs to read about the fascinating differences between the various Heuer back-plates.

Early Back-Plates

Ed. Heuer

Heuer-Leonidas S.A

Sears, Roebuck &Co

• base material: brass or aluminum
• coating material: chromium, profectus or black anodized
• number of holes to attach plate to the dashboard: two, three or four
• cut-out for crown or none
• marking on the back: none, number, Ed. Heuer & Co., Heuer-Leonidas, S.A. or Sears, Roebuck & Co.
• finish of the back: smoothe or matte
• overall thickness of the plate: 3.4mm or 3.8mm

Now let's work through the chronology of the back-plates with an eye on these specifications:

• Early Back-Plates:
  • chromium coated brass;
  • three holes for the Autavia and Auto-Rallye;
  • cut-out for crown;
  • smoothe back either has no marking (earlier) or a number (later);
  • 3.8 mm thick

• Ed. Heuer & Co.:
  • brass plate is coated with either chromium (earlier) or profectus (later) [see the photo above or click here to see the difference in the color of these finishes];
  • two, three or four holes to attach plate to the dashboard;
  • back has smoothe finish (earlier) or brushed finish (later) and is marked Ed. Heuer & Co. Swiss;
  • 3.8 mm thick