The Roadlink extender can blow your road bike gears more into the mountain world. You don't have to change the derailleur along with the cassette. Just insert this "foot extension" between the foot and the derailleur which can literally do wonders. Without sacrificing shifting precision, you get the option of fitting up to a 40-tooth cassette on your bike. Works great with both single and dual converter systems. Weight: 17g Material: 6061 aluminum Package includes: stainless steel screw Recommended tightening torque: 8-10Nm Made in USA