Soda companies use baseball for any number of promotional tie-ins, both today and over the sport's history. Today, Coca-Cola bottles include under-cap codes that drinkers primarily redeem for more Coke stuff in a vaguely creepy, self-perpetuating cycle. Back in 1967 and 1968, on the other hand, black-and-white player mugshots greeted the refreshed cola drinker. If you're a caffeinated collector like me, win-win!
Coke divided their late-60s caps into a bunch of groups. Most stick to specific teams, but a few are cross-league "All Stars" like today's Rusty Staub. What you see is what you get, with text framing a cropped floating head under a rubbery coating.
Coke spread their sets across several soda brands, so you'll see players on Coke, Tab, Sprite, Fresca, and Fanta caps.
Diet sodas are so popular today, it's easy to forget how feminized the "dieting" market use to be. With men becoming more body-conscious by the 1970s and our FDA considering Tab's saccharine sweetener a possible carcinogen, 1982's introduction of Diet Coke quickly claimed their low-calroie cola market. Coke now positions Tab as a bridge between the energy and soda drink markets.
Value: Player caps run $2-3 online and stars cost a bit more. A courteous dealer from the 2007 National gave me Mr. Staub gratis, a reminder that being friendly and sociable at shows has fringe benefits!
Fake / reprints: It would be tough to reprint a bottle cap.