Ghetto, 20 marks 1943, aluminum, most dangerous counterfeit, late 70's, has secured triangle

Counterfeit minted to the detriment of collectors.
Great rendering of the details of the original, including the engraved "cracks" of the stamp - on the obverse under the date, on the reverse under the R in the word "MARK". It even has a convex triangle under the R in MARK - which is normally a safeguard of originality.
The most dangerous forgery, in GDA classification stamps F6/F6, in Bulkiewicz classification type VI.
Old forgery, now about 50 years old, collected by collectors similarly to Majnert forgeries.