Progressive Suspension 970 Series Piggyback Shocks - 12 1/2in. - Gloss/Matte Black 970-1001B Progressive Suspension does it once again! Designed for performance oriented twin shock bikes Features piggyback reservoirs, high-pressure gas charge and deflective disc-valving, all packaged in a mono-tube style body Includes progressive rate springs The threaded pre-load adjustment and external compression adjustment knob allow for fine tuning to provide optimum performance rider weight or riding style