I have 23' of ducting with 2 90 degree bends. I bought the kit and the four extra extensions. Easily cleaned the ducts with no problems. Two tips: Read the instructions. And, if you need the extension kit, don't buy it. It costs $3.00 more than the 10 piece cleaning system. The extension kit is just 4 rods, identical to the 4 rods in the cleaning system for more money (?).