This is a steam vent coolant crossover system for an LS based engine. Many LS engines did not come from the factory with a four corner balanced steam bleed off system. This can result in different temperatures in different cylinders of the engine along with other failures. Included in your purchase are: (4) corner manifold ports machines from 6061 aluminum and anodized black (1) 5 port center manifold black anodized All hardlines shown bent from 304 Stainless Steel All fittings shown Stainless bolts for corner manifolds This system is very high quality and we hand bend and check each line to ensure perfect fit! The front common line supplied that will return steam and coolant to your radiator will accept a rubber hose. This line can also be removed and you may run an AN style line directly to the manifold block. This system is ideal for nitrous, turbocharged, super charged, procharged and other high performance applications on an LS1 engine. This system will fit all models of 5.3, 6.0 5.7 ls1, ls2, ls3, ls4, ls6, ls7, ls9, lsa, lq4, lq9, lm7, lsx, rhs and other ls applications. This has been tested with Edelbrock Victor Jr, Edelbrock Super Victor, Edelbrock Pro Flo XT, and Holley Hi Ram Manifolds. Will fit many others!