? UN (Unified) Full Profile Internal Threading Inserts ? To form a quality complete thread profile including the crest. For every thread standard and pitch a separate insert is required. Inserts are supplied in packages of 10 inserts and a screw. ? Insert Grade SelectionChoose the CARMEX grade specifically formulated for your application. ? BXC: PVD TiN coated grade for applications that require Super Low cutting speeds (such as very small diameters in which even high rotational speed generates only a low cutting speed). ? T20: PVD TiN coated grade for low cutting speed. Works well with wide range of stainless steels.