TG may stand for tour grind.
Over the years I've been a huge fan of the Cleveland classic wedges 485, 691, 588 and so on. As I recall there was nothing especially compelling or desirable about the tour grind in terms of improved performance for a good amateur player. I believe was just a good all around wedge that could do the job in multiple conditions.
Sorry I don't have have more specific or useful info.
Enjoy!