I don't see a UPC barcode on the packaging any where. Is there one?
The first barcodes started appearing in the mid 1970s and I think by the time you get to the early 1980s it was pretty uncommon to see a product without one. That may put your filter in the late 70s/very early 80s.
The first barcodes started appearing in the mid 1970s and I think by the time you get to the early 1980s it was pretty uncommon to see a product without one. That may put your filter in the late 70s/very early 80s.