Just pick your guitar and spin the wheel to select the proper Gibson string for the job! This item is from 1970. We started selling Gibson guitars in 1972 so this is probably when we got it and I've had it all these years. Never used it but I guess it was a good idea. Considering that it is cardboard and almost 50 years old it is in EXCELLENT CONDITION with just a one or two small marks. An interesting little bit of Gibson and guitar history in general.