Klein Tools 53717 Flex Auger Bit with Screw Point, 3/8 x 72-Inch

The shank on the 53717 measures 0.4 inch, so it needs a chuck that opens past 3/8 inch. A 1/2-inch keyless or keyed chuck on a standard right-angle or hole-hog style drill takes it without an issue. A 3/8-inch chuck will not close on this shank.

Overall length is 72 inches, so you can reach roughly six feet into a wall cavity from a single opening, minus whatever length stays in the chuck. For longer runs, Klein makes a flex bit extension, Cat. No. 53723, that the bit is made to work with.

It cuts a 3/8 inch (10 mm) hole. That is enough for low-voltage runs, coax, or a single small cable pull. If you are pushing 12/2 or 14/2 romex through studs, or pulling more than one cable per hole, step up to a larger diameter flex bit.

The 53717 has a fish eye hole on both ends. Drill the hole, tie or hook your wire to whichever eye is accessible, and draw the bit back out to bring the wire with it. Two eyes means you can pull from either direction without repositioning the drill. The back of the bit is tapered so it retrieves out of the hole cleanly.

Klein lists two companions for this bit: the Flex Bit Placement Tool, Cat. No. 53715SEN, which lets you aim and hold the bit where you want it inside the cavity, and the Flex Bit Extension, Cat. No. 53723, for reaching beyond 72 inches. Neither ships with the bit. The bit itself comes with a reusable protective case for the auger head.

A rigid auger only works when you have straight-on access to the stud. A flex bit like the 53717 has a spring steel shaft that bends around the cavity, so you can enter through a single cut-in box or switch opening and drill through plates and studs you cannot see. The screw point tip pulls the bit into the wood instead of forcing you to push a flexing shaft. For open framing before drywall, a rigid auger is the faster tool.

No. Klein's own warning on this bit is to never use it on or near live electrical circuits. Kill the circuit before you drill into a cavity that may hold energized conductors, and wear approved eye protection. This is a bare steel bit with no insulation rating.

The shaft is spring steel, chosen specifically to resist deformation, so it flexes under side load and returns rather than taking a set. It is still a 3/8 inch shaft at six feet of length, so let the screw point pull and avoid heavy side pressure on the drill.