I had one of these in a while back for some repair work, I was wondering what it was too.
It had a DG sticker on it but I highly doubt it was DG.
The chain adjuster with it was stamped Pro-Tec
Extrusion profiles are available in many different shapes & sizes, square edges etc. do not indicate age or grade, but simply the profile that was readily available at the time.
The one I repaired seemed to be "old"