US$ 489.07
They have a slight wedge shape that grips both sides of the slot
Part Number: 100C275NCPL2Z
Part Number: DUR385-95
but soft enough to avoid marring delicate work surfaces
1/4"-120 HSS Single Flute Countersink Quantity:5 They have a slight wedgePart Number: BIT DEWSFC1 4 120 Countersink Angle: 120 Degrees Material: High Speed Steel Overall Length: 2" Size: 1 4" Finish: Uncoated (Bright)