Mathews ROCK MODS come standard on the Chill-X and will also fit Chill, Chill-R and Chill SDX. They have an integrated draw stop that stops on the cables - not on the limbs - no torque issues on a split limbs! It gives a rock solid back wall for shot-to-shot consistency. In short, theyíre fantastic.
85% is standard and we only stock 85% Rock mods in our Perth Archery Store. Youíll get a 5-10fps gain swapping out the 85% for a 75% Rock Mod. Itís a small gain and itíll depend on your draw length and poundage. Try it though, itís about feel and personal preference . Saying that, most bowhunters prefer the lighter holding weight.