This degree wheel is mandatory for professional engine builders Accurately measures several timing functions of an engine: camshaft centerline, valve timing, TDC, BDC, etc. Made from heavy gauge metal with a silk screen finish for long-lasting use in shop or track environments Adapter included to fit virtually any engine For mounting Degree Wheels, use Crankshaft Socket No. 61755 or No. 61756 for Small and Big Block Chevys, and No. 61757 for LS Series Engines with keyway