Install these inserts into a matching holder to cut external or internal threads on a workpiece. They are compatible with top-notch style threading and grooving systems, which use a highly-rigid clamping design, resulting in a smoother finish and superior tool life. When the edge on one face is dull, flip the insert over. Choose a holder (sold separately) with a shank size that fits your machine and workpiece setup. Larger shanks are more stable, while smaller shanks fit into tighter spaces and allow for finer cuts.