Very hard wearing professional flat bits, the best we have ever used! Fast, accurate and clean cutting, they have a self-cutting threaded point to draw them through the work, with two cutting spurs that ensure a clean finish, scoring entry and exit holes. Tip and cutting edges are precision ground for a precise hole size; the paddle is contoured for fast chip removal. Suitable for hard and soft woods, great for boring through joists. They all have a 1/4" hexagonal shank that ensures they do not slip. The threaded point pulls the bit through so extra care must be taken if used with a power drill. Speed information is stated on the packaging, dependent on the size. A quick release 152mm long extension is available separately.