Metal drill bits of type HSS-R are strong twist drill bits suitable for particular ferrous and non-ferrous metals and also hard plastics.
Metal drill bits of type HSS-G, precision-ground selfcentering drill tip, are designed for drilling in alloyed and unalloyed steel,
non-ferrous metals, gray and malleable cast iron, and also hard plastics.
Metal drill bits with TiN coating are the most long lasting among steel drill bits. They have the same characteristics as HSS-G
drill bits, except a longer service life.