Boyesen's patented dual-stage design incorporates a specially shaped top reed and a ported bottom reed The top reed is lightweight and resilient for crisp throttle response at partial throttle or low RPMs. The stiffer, bottom reed is ported to provide maximum flow and horsepower at higher RPMs More Air Flow. The dual-stage design allows you to replace your stock reed stop with a Rev-Plate which permits the reeds to open freely and function efficiently More Air Velocity.
A great product for the money. I installed the reeds on a 1982 Suzuki PE175, which required removing the cylinder. The original reeds on this bike are made of steel! Boyesen was a great inventor, we're lucky he worked in the motorcycle industry.