A coilover is an automobile suspension evice, short for "coil (spring) over strut". It consists of a shock absorber (British: damper) with a coil spring encircling it. The shock absorber and spring are preassembled as a unit prior to installation, and are replaced as a unit when the shock absorber has leaked. This provides for optimal damping without torsional loads. Some coilovers are adjustable for ride height and hardness as well using a simple threaded spring perch similar to a nut.