Charge lines without worry with the new RockShox Charger 3. 1 RC2 Damper Upgrade Kit. The Charger 3. 1 RC2 gives us a wider range of damping adjustments so we can tune our fork to our specific riding style, and it is littered with high-speed compression, low-speed compression, and low-speed rebound adjustments. This upgrade kit includes the Charger 3. 1 RC2 damper, and RockShox's ButtCups while helping to reduce vibrations from the trail.