I think that is a Stoeger .22 rimfire Luger magazine.
It is for the 'Stoeger' mfg'r .22cal Luger pistol and is an orig as would have come with the gun at the time when mfg'rd.
Sometimes confused with the 'Erma' mfg'r .22rf Luger pistols/magazine of around the same time period..
The orig Stoeger magazine had a white plastic follower which over time has usually darkened some what by now.
The absence of a visible magazine spring in the cut-out in the body is a good clue to it being for a Stoeger and an original.
There were aftermarket mags for the Stoeger quickly placed on the market.
Those repro mags had a green colored plastic follower as a rule AND they did have a magazine spring visible thru the cut out in the magazine body.
The ERMA mfg magazines and their repros for their line of .22cal 'Lugers' all had the visible mag spring as far as I can recall. None off the mags from either mfg are interchangeable with the other maker as far as I know.
....Another quick ID point for the Stoeger mag is on the LH side towards the top is a shallow, rectangular shaped punch mark into the sheet steel from the mfg'rg process.
None of the orig mfg magazines for either of the mfg'r '.22 Lugers' are an inexpensive item to buy as a rule.
