This is an ATI super damper for the Cadillac ATS-V. The factory rubber crankshaft damper can deflect at high RPM and greater than stock power levels which can eventually lead to excessive crankshaft vibration. In extreme cases this can lead to deflection and dislodging of the reluctor wheel. 

To read more on ATI's super damper technology and benefits, read their write up found here. 

The patented ATI Super Damper is the only crankshaft damper designed exclusively for high performance GM engines.

• Eliminates torsional crankshaft vibrations
• Exceeds SFI 18.1 specs
• Black zinc chromate finished
• Tunable, rebuildable, and extremely efficient at ALL RPM
• Laser engraved 360° timing marks

The ATI Serpentine Super Damper contains grooves for the serpentine belt machined into the outer bolt on hub.  Our version of the ATI uses the stock length belt. 

The stock crankshaft bolt is torque to yield and needs replaced when servicing the damper, we have replacements found here. 

Fits: 2016-2019 Cadillac ATS-V. May fit Cadillac CT4-V Blackwing LF4 and LF3 engines including the CTS V-Sport, but we have not confirmed fitment.