HSS drills stay sharp up to 10 times longer than carbon steel models; carbide outlasts HSS by another 10:1. These are the drills of choice for production work where you need a bit that can take continuous use.
As with router bits, a carbide tip in a bit quickly repays your initial investment. Guaranteed to be within 0.001" of the stated diameter.
Shanked to size up to 3/8"; larger bits have 3/8" shanks.