Hi All, I know I seen this once before on the forum, but can't locate it now, nor do I remember what the out come was.
So, can any one help I.D. these for me. I first thought a brass washer for maybe a pneumatic thermostat or on a controller, but I'm leaning more towards a coin. I have been finding these in the same area I found my Chinese Coin, which had a square hole but also had writing on it.
Thanks