MRP Progressive Spring Experience the best of both worlds with the MRP Progressive Spring. Coil suspension has always been superior for small bump sensitivity, but always fell short not being progressive. The MRP Progressive Spring has solved this dilemma for their Hazzard rear shock. Experience a coil shock that is supple off the top and ramps up at the bottom. The coil is produced in many lengths and spring rates to accompany any size rider on any MRP Hazzard shock. Finally run a coil shock on your favorite bike, even if it doesn't have a progressive suspension curve. Features Progressive coilcombines the benefits of air and coil shocks Compatible with:MRP Hazzard rear shocks Multiple spring ratesfor every size of riders No special tools neededfor install to shock SPECIFICATIONSShock Stroke65mm Coil Lengths119, 122, 124, 129, 130, 133mm Spring rates300-360, 350-420, 400-480, 450-540, 500-600, 550-650 lbs. | Mrp | Progressive Springs 450-540Lb / 65Mm Stroke, 129Mm Long