For  Older  Moulders 4 Knife Steel Cutter Heads for self centering sleeves (not included, we do sell them) spindles. 20 degree hook angle 6" Diameter 4" cut length 16-60° corrugations  Uses 1/4", 5/16 or 3/8" corrugated back steel made in USA step up and replace your square molder heads and see a profit from ..