845 1-flute Countersink Bits, 16.50 x 40 mmHigh quality 1-flute countersink bit by Wera. For countersinking and deburring. The hexagon shaft ensures very good power transfer, vibration-free and score-free working. Perfect chip removal and long service life. 1/4", hexagon, suitable for holders as per DIN ISO 1173-D 6.3.