A combined taper drill, countersink and counterbore creates the perfect starter hole for screws in a single pass. You can alter the shank length with the included Allen key and then simply drill to the appropriate depth depending on whether you want the screw proud, flush, or sunk below the surface. The matched plug cutter produces an accurate, concentric plug that fits the counterbored hole perfectly. There are cheap versions of this type of tool on the market, but we have gone for the top spec Japanese high speed steel option. This gives maximum service life and no problems if you work with hard exotics or occasionally need to countersink through an applied brass plate for example. Sold as a set.