end, which allows the climber to clip in the rope. These devices are later collected again, usually by the followers when they ascend themselves. In sport climbing there is usually only one climber. The climbing partner remains on the ground and belays the lead climber while they ascend the sport route. In sport climbing protections are usually permanently attached to the rock face in the form of drilled bolts or chains which are used for attaching quickdraws directly. The quickdraws are either placed by the lead climber during the ascent or are placed beforehand. Fall distance and impact Distances between pieces of protection can range from or more, although most often the distance is between . At any point, protection will be placed so that the distance to the most recently placed protection will be at most, half of the length of a possible fall. For example, if a leader is above the last piece of protection, any fall should be a maximum of . Realistically, the fall would likely be somewhat longer due to rope elasticity and slack and give in the overall mechanical system. If a lead climber, starting from the ground, approaches twice the height of the last piece of protection, there is danger of a ground fall (more commonly referred to as "decking") in which the falling climber hits the ground before the rope goes tight. The severity of a fall arrested by the climbing rope is measured by the fall factor: the ratio of the height a climber falls before their rope begins to stretch and the rope length available to absorb the energy of the fall. (A leader may reduce their fall factor by using "protection", equipment that attaches in some way to the rock, allowing the rope to pass through it.) As the rope begins to stretch, it absorbs the energy of the fall and slows the falling climber. The more the rope is stretched by the force of the faller, the more intense the force it exerts on the faller, and the more severe any effect of that force. For this reason, a fall of is much more severe (exerts more force on the climber and climbing equipment) if it occurs with of rope out (i.e. the climber has placed no protection and falls from above the belayer to below—a factor 2 fall) than if it occurs above the belayer (a fall