In a rescue, firemen could extend Denison's hydraulic ladder to windows as high as 113 feet. But rather than clamber up the ladder, the firefighter would hop on, and the rungs would roll up at 200 feet per minute—more than twice the average climbing speed of a firefighter weighed down by 130 pounds of gear. The firefighter would ride to a window, load unconscious victims into a rescue bag, hook the bag to the ladder, and shift it into reverse to bring the person to safety. Denison says it can now take up to 15 minutes, and sometimes several men, to carry one victim down a ladder from 10 stories. He estimates that his ladder could lower four people to the ground in less than four minutes.