Pro Comp's 2.5 Pro Runner Monotube Reservoir Shocks design delivers superior performance over traditional twin tube, hydraulic shocks. The vehicle specific ride tuning was derived after extensive dyno and real-world testing. The result is multi-stage valving that optimizes ride quality and handling characteristics for your specific application. The brushed, zinc plated, clear coated, monotube shock body is nitrogen gas charged to eliminate performance-robbing cavitation during compression and rebound, allowing the shock to dissipate heat more efficiently, drastically reducing shock fade. The external reservoir allow for additional fluid capacity and maximum heat dissipation.