BHS-3 3" Boring Head Set, including R8 Shank and 3/4" Carbide Boring Bar Set Go to amazon.com Related posts Top 4 best boring head 3/4: Which is the best one in 2022? FeatureIncludes 3" Boring Head, R8 Shank, and 12 piece 3/4" shank carbide tipped boring bar set.Boring Head Thread: 1-1/2"-18 DescriptionSet BHS-3 includes model BH3, 3" boring head, R8 shank, and 12 piece 3/4" shank carbide tip boring bar set.