Accoding to SSK-Book this camera was made at GOMZ as prototype in 1949. Two cameras are shown in the book with the serial number engraved on the top plate (490006 and 490066). All three cameras (in the book and on Ebay) are absolutely identical, but the last one hast no s/n at all. Could it be the very firt one (pre-prototype)? I see this camera for the first time.