Made from the highest quality chrome-silicon spring wire available today, these springs can easily handle the abuse of hotter cams and high revving. Progressive design means no recognizable harmonic frequency. Combined with titanium retainers and machined valve locks, your valve train will be moving less mass than with O.E.M. components. This will allow your bike to rev faster quicker and retain much more control over the valves. Sold as a set. Note: Image is for display purposes only, actual part may vary based on fitment. Detailed Specifications: Fits 2001 - 2006 YFM660 Raptor. Required with stage 2 CAM. 5 count.