The 50 you show seems to be like one I have, also in white. See photo. I have many variations of these numeral chips. I wonder if USPC made most them over the years? The chip I post originally is quite different than these. Most notably, the beveled edge. In the extra link below you can see how many variations I have of the numeral 5. I do wonder if there may have been many companies making these chips, though I'm told only USPC and Burt Co. were chip makers.