Presto 6 Pcs 90° HSS SS Countersink set 

Containing 6.3mm, 8.3mm, 10.4mm, 12.4mm, 16.5mm, 20.5mm

Universal tool for deburring and countersinking. Used to produce countersinks for screws and a chamfer for tapping. Advantages are chatter-free working and easy regrinding at the cutting face.