Oakley "Flak" Sunglasses????

A mystery with this pair of sunglasses.  Oakley when it first started out did not put name/model number on glasses. This could be one of those, OR it could be a "faux" pair.  Looking them over, they have many of the quality hallmarks of Oakley.

Black frame, half rim, with nose and arm pads. Oakley printed on nose bridge and the arms have icons.

Grey lenses

Pre-owned, normal wear.

No case

Value marked lower than other Flak's in auction.