A drill attachment for making shallow pits in various surfaces. The pits are designed to allow the heads of screws to sit below the surface level, so they don't stick out and cause injuries. They also look much neater when countersunk and offer a more secure joint.

To use, just attach to the drill as you do a drill bit and press firmly into the pilot hole you drilled for your screw. The longer you drill with the countersink bit, the wider and deeper the countersink hole will be. Screws with larger heads can be fitted flush by making the hole bigger in this way.