Edelbrock's Performer/Classic IAS shocks feature the patented Inertia Active System. This exclusive design switches instantly between a soft and a firm circuit for superior handling and a smooth ride. Because it has the ability to switch between circuits almost instantaneously, total control over road surface irregularities is unparalleled with no compromise in handling as in conventional shock designs. (Each).

Performer IAS Shocks	Classic IAS Shocks
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Performer IAS Shocks were first shocks to include the Inertia Active System. They have a distinctive red powder-coated finish.	Classic IAS Shocks include same features as the Edelbrock Performer IAS line but with a gunmetal gray powder coated finish and classic Edelbrock logo.
Edelbrock Application Guide