ACDelco 903-001RS Professional Ready Strut Premium Gas Charged Rear Suspension Strut and Coil Spring Assembly Pre-assembled kit is safer than assembling individual components High quality strut rods are constructed of high carbon steel, straightened, micro-finish ground, quality chrome plated, and with a diameter equal to or greater than the original equipment Micro finished pressure tube bore for smooth operating surface of piston and seal Powered metal pistons resulting in precision tolerance for crisp blow-off valving Contain high performance hydraulic oil with friction modifiers and anti-foaming agents for consistent damping force through a wide operation temperature range