Kernmantle rope () is rope constructed with its interior core protected by a woven exterior sheath designed to optimize strength, durability, and flexibility. The core fibers provide the tensile strength of the rope, while the sheath protects the core from abrasion during use. This is the only construction of rope that is considered to be life safety rope by most fire and rescue services. Parachute cord Parachute cord (also paracord or 550 cord when referring to type-III paracord) is a lightweight nylon kernmantle rope originally used in the suspension lines of parachutes. This cord is useful for many other tasks and is now used as a general purpose utility cord by both military personnel and civilians. Use as climbing rope One of the uses of kernmantle rope is as climbing rope. Nylon ropes that were used in yachts for hauling were tested and found useful in climbing and caving and are now the modern standard. The German company Edelrid introduced the first kernmantel rope in 1953, which revolutionized fall prevention. Hemp climbing rope became a thing of the past and rope breakage was greatly reduced. In 1964, Edelrid and Mammut both developed dynamic ropes capable of withstanding multiple falls. These became the forerunner of the modern dynamic climbing rope. Although there were occasional innovations, the rope used today is similar in construction, strength, and durability across manufacturers. Overall there is a huge variety of climbing ropes available for different purposes; for instance, there are well over one hundred different dynamic single ropes (the most popular rope system in climbing). Kernmantle ropes are still used in sailing and other sports, but the technical requirements are usually not as rigorous for such purposes as for climbing. Small kernmantle ropes are commonly called accessory cords; they are often used to make prusik knots and loops or to attach accessories such as chalk bags. Depending upon the ultimate use of the rope, one or more of its many characteristics (material, structure, finish, color, strength, durability, elasticity, flexibility, price, etc.) are altered, sometimes at the expense of other properties. For example, rope used in caving is generally exposed to increased abrasion, so the mantle is woven more tightly than rope used in climbing or rappelling. However, the resulting rope is cumbersome and difficult to tie knots in. Kernmantle construction may be used for both static and dynamic ropes. Static ropes are designed to allow relatively