4" BORING HEAD SET 6 PCs CARBIDE BORING BAR WITH R8 SHANK 4 INCH BORING 1'' MILL Go to amazon.com Related posts Expert choice for boring head set FeatureBoring Head Dia: 4".Boring Head Height: 3-1/2"Boring Capacity: 15~320mm.Max. Offset: 1-5/8".Boring Bar Dia: 1". DescriptionBoring Head Dia: 4". Boring Head Height: 3-1/2" Boring Capacity: 15~320mm. Max. Offset: 1-5/8". Boring Bar Dia: 1". Cross Hole Dia: 1". Min. Graduation: 0.0005". Bar Thread :1-1/2"-18 Shank: R8. Quantity of Boring Cutters: 6 PCs.