I was a roofing and general contractor in Los Angeles for 30 years. In 1994 my 40 ft. ladder was blown over by the wind. It missed a mother and a very small child walking hand in hand by just inches. As aresult of that accident, I designed something that would prevent this accident from happening. The Safe T Climb unit is completely universal. It works with any type extension ladder and on any type roof. Our products are proudly made in the USA. Safe T Climb "The extension ladder anti-fall device" is being used by everyone from the homeowner to the military.