7-Piece, Superior USA-made, machine-shop grade tooling that delivers precision, quality, and productivity. Turned, Not Stamped. Superior Proprietary Fitting vs. Soldering. These premium threaded drill bits are machine-shop grade tooling used in a variety of applications where precision and productivity are required. The problem with most other bits is that they are soldered together and can become loose in the holder and even separate as the temperature of the bit and material being drilled increases. Moreover, typical bits on the market are limited by the hardness of the steel they can cut and the accuracy that they fail to deliver. ProMAXX PSSC drill bits have a proprietary fit into the holder, eliminating the inexpensive soldering that can delaminate and cause them to separate. Because these bits are turned out of cobalt steel, they are capable of cutting into extreme hard materials including Rc. 55, which is TWICE the capability of any other drill bit.