The product PT1014BL12 has a size of 52 mm. is it intended final including the frame or the internal circle of the instrument?
All the 52mm instruments are designed to fit in a 52mm hole.
The outside of the bezel will br greater by a few mm depending on the manufacturer.
The size is quite historic it goes back to the early 1950s when the gauges were made by Smiths Industries in England.
The hole was an imperial size of 2 inches. This has followed through since.
24th March 2025