Drill inside walls and between floors to install electrical wiring without cutting extra access holes. The shaft on these bits flexes for a long reach in any direction. To install wire, first strip the end and attach it to the small hole at the tip of the bit. Then pull wire back through the drilled hole. Also known as bell hanger bits.

These bits are hard enough to drill through masonry and concrete as well as wood. Feed electrical wire, data cables, and phone lines through walls with the same tool used to make the hole. Once you've drilled, insert wire through the bit's hollow shaft to the other side of the wall. These are simpler to use than flexible-shaft bits since you do not need to strip the end of the wire. Also known as bell hanger bits.