Before Christopher became a saint, he tried going a different direction and decided to be a follower of Satan. Figuring that this was probably not the best move in the long run, he chose to join the forces of good, and started a career as a follower of Christ. This was a pretty big win for the good guys, because Christopher was three times taller than you.
The tale written in the saints compendium called The Golden Legend held that Christopher was 18 feet tall. As the writing of the time put it, he was 12 cubits (a cubit being 18 inches). But apparently instead of being the patron saint of choke-slams or of little person juggling, he became the patron saint of traveling. Consequently, images of the Christian Goliath being really big were scattered around Europe.
The most important event in his life of being tall and wasting it just walking around was putting a 3-year-old Jesus Christ on his shoulders and wading across a river, hence the name Christopher ("Christ bearer"). You'd think Christ would be the last guy who'd need someone to carry him across a river, but in a story with a guy as tall as a building and a 3-year-old Jesus traveling on his own, accuracy may be secondary.
On top of that, when it came time to port the story of St. Christopher into Eastern Orthodox doctrine, a translation error pretty much transmogrified the guy. You see, Christopher was a Canaanite (which at the time of Christ meant that he was essentially an Israeli), but this became "canine." Hilariously, artists and iconographers just went with it and turned the giant into a damned werewolf without a second thought.
Saint Christopher was not a werewolf, but after his conversion to good, he only wanted to help people. He traveled around looking for those in need. His gigantic size makes his abilities even stronger and his presence well known.
This small token will implement the facets of pure protection --- and who doesn't want the spirit of a helper of Christ, who is taller than thou to be watching over them? If you are in need of help, or simply want protection to better your life, then this is the charm for you!