RUKO HSS Flat Counter Sinker with Fixed Guide, Fine Grade for Through Hole, DIN 373, Bright Finish, 12.5 mm Diameter, 100.0 Length, R102405

ManoMano

Ruko 102405 pivot drill bit in HSS, 15 mm, ideal for cylinder head screws, bolts, and hex nuts. Suitable for steel, cast iron, non-ferrous and lightweight metals. Optimal at low cutting speeds. Sold individually.

Amazon

To produce cuts for cylinder head bolts, hex bolts and nuts. Great for burr-and chatter-less sinks in steel, cast iron, non-ferrous and light metals. Great results at low cutting speed.