The red string bracelet is worn on the left wrist by people with anorexia, specifically people who participate in the Pro-Ana movement. They do this to keep reminding themselves that they're doing good when they don't eat and to try to find other anorexics in real life.
Bulimics wear a Blue string bracelet on their right wrist for the same reasons
An energy drink. Or football team owner. Or racing team owner. Or racing team sponsor. Or air race hosting company. Or hockey team owner. Or esports team owner. Or magazine brand owner. Or marathon holder. Or general sponsor of many sports. Or a looot more things.