Manufactured from a combination of 7075-T6 and 6061-T6/651 aluminum our drive mandrel was designed to be rugged, reliable and versatile. Our drive mandrel is mounted directly to the face of the balancer (with or without a trigger wheel) eliminating the long bolt that retained both a mandrel and balancer to the crank shaft. Your balancer is now (reliably) retained by a separate bolt. The 1.250″ hex drive nut/pulley retainer, manufactured from 7075-T6 aluminum and hard anodized, is splined to the mandrel shaft. With the positive engagement of a spline your engine can now be manually rotated in either direction, when valve or cam adjustments are required, without (inadvertently) loosening or over tightening the balancer retaining bolt.