SnyperBob
Active Member
Wikipedia:
Installer bits are available in various materials and styles for drilling wood, masonry and metal.
A variant of the installer bit has a very long flexible shaft, up to 72 inches (1.8 m) long in the US, with a small twist bit at the end. The shaft is made of spring steel instead of hardened steel, so it can be flexed while drilling without breaking. This unique design allows the bit to be curved inside walls, for example to drill through studs from a light switch box without needing to remove any material from the wall. These bits usually come with a set of special tools to aim and flex the bit to reach the desired location and angle, although the problem of seeing where the operator is drilling still remains.