The quick change floating tap holders of series 198 are devices for threading operations on machine tools. The family is designed to allow rapid installation of the tap or die and for use in repetitive machining. The operating principle is based on axial compensation provided by internal springs that allow controlled axial movement during machining; this function is present during reversal of the direction of rotation. The system also includes a slight radial float useful for absorbing possible misalignment between machine spindle and workpiece. Permitted applications concern threading operations in mechanical production. Fields of use include precision mechanics, automotive and serial machining on machine tools. Selection criteria are based exclusively on the available real parameters: tap capacity M3–M12 or M6–M20, shank diameter d1 from 20 mm to 40 mm and sleeve size 19 mm or 31 mm. Differences between variants concern the combination of capacity, shank diameter d1 and sleeve size. From a technical point of view, the tap and die holders are made of highly alloyed steel, hardened and fully ground; the production cycle is carried out with high-precision machine tools and is subject to rigorous controls.