SB-Chevy
Includes eight plugs to block the oil return holes in the lifter valley above the cam. This redirects the oil to the front and rear return galleries into which the screens are fitted, returning the oil directly to the sump area instead of dumping it on the crankshaft with consequent increased windage and lost horsepower. BB-Chevy
Includes four stainless steel mesh screens for over the holes in the lifter valley to keep debris in that area instead of entering the oiling system. The oil itself is not restricted or redirected.