QA1 63 Series Sealed Threaded Body Twin Tube Shock Absorber - 7in Stroke - 5-650 Valving - AluminumThe 63 Series is a sealed non rebuildable version of the 62 Series. These are most commonly used in coil over applications on both dirt and asphalt tracks. The twin tube design gives excellent feel and grip across all track conditions, but they really shine when there is a lack of grip. Built as a spec shock that could be used at specific tracks or series, the 63 Series can be used in any late model or modified.