Proper adjustment of shock "sag" can have a substantial impact on handling and comfort, yet few riders ever make the adjustment. It's quite simple and quick, but you'll need a shock spanner to set pre-load. The CruzTOOLS spanner is made of tough stainless steel, and is compact enough to fit inside your tool kit. It's designed to fit most major makes of shock absorbers. Made of tough stainless steel. Compact enough to fit inside your tool kit. Fits most major makes of shock absorbers.