I've got a roll that says pet.
It's a sort of traslucent gray.

Pet is not as rigid and tends to stribng more.
Pet is what's primarily used in injection moulding the glycol was added to make it better for 3d printing.
hence pet-g
polyethelene terapthalate-glycol.

Pet-g is much better for 3d printing so these days you don't really see the original pet for sale.