This was one of a series of Gibson cartoonish adverts from around 1973 - 1974. This particular one features an SG standard but also mentions the budget SG1 and SG2 models. The text of the ad reads:

Show us a lead guitarist who's never heard a Gibson SG ... he's got wooden ears, no question. Because Gibson SG's are as widely used as any guitar can get. Except for the SG1 and S G2. They’re brand·new lead guitars with the same long, lean looks and rapid response that you expect from any Gibson solid electrics like the well loved SG Standard and SG Special which have been given a brand- new look and sound. The prices are right, too. Nicely there in the lower register So if your pocket wont run to goldplated pick-ups you can still get real Gibson quality without straining yourself Why mess about with a bummer? A genuine Gibson SG makes it all so mueh easier And theres plenty to choose from Send off the coupon now.