AIR SPRING & STRUT ASSY; Grand Cherokee L; Left; Code ZDB. A shock absorber is a device that controls the spring oscillations when the vehicle goes over various road irregularities, so the vehicle's tires remain in contact with the road. In some cases, shock absorbers have a secondary function as a suspension limiter to prevent the suspension from either over-extending and/or over-compressing. Air Suspension Spring. Part has related components that cannot be reused/reinstalled; lock nut and nut. Suspension Code:ZDB. Absorber. STRUT.