5.11 refers to a specific rock climbing difficulty level in the Yosemite Decimal System, where 5.10 was the hardest climb and 5.11 was almost impossible, but occasionally someone would complete it. The name "5.11" was used by Royal Robbins, one of the pioneers of American rock climbing, to describe the first pants he produced that featured the trademark tactical strap and slash pocket design, which were originally developed for rock climbing. The 5.11 Tactical brand was later established and primarily targets the market of military, law enforcement, and public safety personnel, offering outdoor clothing, footwear, uniforms, and tactical equipment.