There are a number of warranty cards on view here and other sites that list the model as ASG-22 - so it isn't a typo. I also remember (it is so very hazy - lol) that there was some sort of revision between the ASG-2 and ASG-2.5.
I just received a pair of ASG-22 and wondered about the revision - and what it was supposed to represent in the progression. I figured that it was similar to the succession of the ASG-1, e.g.... ASG-1.1, ASG-1.2, ASG-1.3 and so on. Each revision affected the tuning in some way - I wonder what the 22 or 2.2 did the the garden variety ASG-2 - or if it simply meant it was a Stealth model - as many of the 22's I see (but not sure if it is limited to) are Stealth.
Someone out there knows