I bought this timepiece about 1981 and it has been my daily wear both for work and leisure ever since. I’ve had the battery replaced only 3 times so far but then I never use the light.

The model number on the rear is A939-5070 as shown in the photo,  but on the front face it appears to read A939-5050 but the printing is very tiny for my aged eyes even when I zoom the photo!