I got my Lyman M5 over twenty years ago in a trade for "stuff". My guess is it was over 20 years old at the time so a rough guess is they were in production 45 years ago maybe 50. The Lynan M5 is one of the best scales I own and if I see another at a swap meet, flea market or anywhere else I would buy it. Take note that the included weitht is not a test or check weight but used to increase the range of the scale.
Ron