Serious power requires a serious damper. Protect your truck?s engine with the technology preferred by heavy duty diesel OEMs. Superior viscous damper design controls harmful torsional vibration across the entire rpm range. Reduce wear on engine components. Reduce risk of crankshaft failure. Improve timing. Unleash lost torque and horsepower. built precision CNC machined and balanced high-grade steel components. black zinc finish with engraved timing marks. No maintenance required. Trusted by leading performance diesel engine builders worldwide. SFI 18.1 certified. Made in USA.