High Horsepower Engines cause the O.E. tensioner to over tension the primary chain during hard acceleration. The Bump Stop eliminates this over tensioning from the chain adjuster on ‘07 & Later Big Twin (Also ‘06 Dyna). The Bump Stop provides a physical impediment to the ratchet function of the tensioner; While the spring mechanism remains in place for proper tensioning. Made from high quality steel and black oxide coated for corrosion resistance. Machined Grooves help to grind flat to make fine adjustments to the chain tension.