Champion Cutting Tool 308 series high speed steel metric hand tap 3 piece sets come matched with a taper, bottom and plug tap. Ground Thread "H1" limit taps create new threads and clean up damaged threads. Ground threads will achieve close tolerances for safe, secure fastening. Taper taps distribute the cutting load across 7-10 threads. Used for starting a threaded hole. Plug taps are most commonly used, distributing the load across 3-5 threads of champer. Bottoming taps have only 1 to 1-1/2 threads of chamfer and are used to tap to the bottom of a blind hole. Operated in hand tapping wrenches or production tapping heads for general purpose tapping in professional settings. These taps are supplied in standard "H" limits that will provide an adequate "class of fit" for standard tapping applications.