Speedtaps are a very fast way to tap drilled holes. The speedtaps are made from M2 steel and nitrate coated to make them extremely tough. The hexagonal heads on the speedtaps correspond with the head on the bolt so you use the same socket for the speedtap and the bolt. In the past I have used a cordless drill to tap holes in metal but you have to be very careful and have to reverse the tap to break off the chip, but with the speedtap when its used in a impact wrench it means you can power all the way through because of the constant torque supplied by the impact wrench.