New GM harmonic balancer.  This is a stock replacement balancer with a keyed crank groove.  This has 2 6-rib belt grooves.  Some 3.6L's use only 1 part of the pulley (such as the ATS-V).  Fit 13-19 3.6L V6 engines:

13-19 ATS w/ 3.6L-V6

16-19 ATS-V w/ 3.6L-V6 Twin Turbo

NOTE : A balancer removal tool and installation tool are required to install this component.