AMS Lightweight Crank Pulley for the '07-08 350Z VQ35HR engine as well as the 370Z's VQ37VHR engines. This pulley replaces the heavier stock crank pulley (4.7 lbs) with a lighter machined aluminum piece (1.45 lbs), which is nearly a 70% weight reduction. Power and torque gains throughout the power-band! -Metal sleeve on main crank pulley for a positive seal – no leaking main seal! Cheaper units lack this metal sleeve. -Since this Crank pulley is not underdriven like others, you will not experience any issues with your charging or cooling systems during daily driving. In addition, by not being underdriven you may also use a OEM size drive belt. Fully balanced, super light, and super strong! Aircraft grade aluminum construction to ISO 9001 manufacturing standards AMS laser-etched logos Anodized black for an ultimate protective finish and sleek look!