Bosch EXPERT Self Cut Speed Spade Drill Bit 7 Piece Set. Contains the following: 6 x EXPERT Self Cut Speed Spade Drill Bits: 16 x 152mm, 18 x 152mm, 20 x 152mm, 22 x 152mm, 25 x 152mm, 32 x 152mm. 1 x EXPERT Self Cut Speed Spade Drill Extension Bar. 1 x Hex Key. The Bosch EXPERT Self Cut Speed Spade Drill Bits for high speed drilling in wood. Equally at home in all types of softwood, the Bosch EXPERT Self Cut Speed Spade Bit offers efficiency and convenience to professionals who need to drill through holes for cables, pipes, and other hardware installations. Fast drilling is easier with Bosch Tip Technology. Its self-feeding thread provides high-speed drilling with only a little pressure. The clever wave-shaped spade allows for fast chip removal. Fitted with a 1/4in impa.