The Xtreme Travel Shocks have everything the Performer IAS Shocks do and then some.  The feature additional stroke for extreme off road situations.  They also have an additional oil reservoir that mounts separate from the shock.   Edelbrock's Patented IAS Valve combined with High-Pressure Gas Charging provides the Best Ride and Handling of Any Shock Absorber made. During cornering or hard braking the Inertia Valve stays closed.  This keeps the chassis stable and level for excellent handling and reduced body roll. When the wheel encounters dips or potholes, the Inertia Valve opens, and the wheel follows the terrain without transmitting jolts to the chassis for a smoother ride over any surface. Features: Patented 46mm IAS Valve System Additional Oil Reservoir for increased oil capacity and cooling. 5/8" Diameter Nitro Steel Piston Rod for Off-Road Durability Zinc Plated Finish High Quality -6 Braided Stainless Steel Line Sold each