Cable bits are long drill bits that have a hole on the end (an eyelet) that passes through the diameter of the bit. The installer provides a run of cable to the place on the other side of the wall in which the drilling will take place. Once the pass-through hole is drilled, the installer leaves the bit in place, penetrating the wall. Then, on the other side of the wall where the cable run is and the cable drill bit is poking through the wall, the installer passes the cable or wire through the eyelet at the tip of the bit, then goes back to the other side and extracts the drill and bit, pulling the cable through the wall. Items vary by their ability to drill through drywall, wood, masonry or steel, as well as length, diameter and other dimensions. For more specialized drill bits, see our jobber length drill bits, screw machine length drill bits, coolant fed drill bits and taper length drill bits.