A horseshoe on a door is regarded as a protective talisman in some cultures. Horseshoes have long been considered lucky. They were originally made of iron, a material that was believed to ward off evil spirits, and traditionally were held in place with seven nails, seven being the luckiest number. Some believe that hanging a horseshoe with the ends pointing up (U) will trap good luck in the horseshoe to protect the home. Others believe that hanging it heel-side up will allow good luck to flow out to those who pass beneath it.