Shock Absorber Type 643 Competition PWith compression reservoir on a milled mount. The upper mount is precision milled from solid aluminum and integrates the high and low speed compression adjusters. A pressure relief valve prevents hydraulic lock and shields the chassis from uncontrolled jolts under extreme compression. The shock is fully adjustable: 22 clicks of rebound and 22 clicks each for high and low speed compression. Spring preload can be set mechanically or, optionally,