One of the mysteries of the English language finally explained.
A trademark for: any of various cameras made by the Rollei company, especially a twin-lens reflex camera.
1930s; earliest use found in The Trade Marks Journal. From German Rolleiflex, trademark for a range of cameras from Rollei, the name of the company who introduced this range of cameras (further etymology unknown) + -flex (in German Reflex).
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