DRILLCO - 5/16,COUNTERSINK 60DEG SINGLE FLUTE - 36E120A

Single Flute Countersinks should be used when multi-flute countersinks chatter or the hole is too small for a multi-flute countersink to enter.
most common angles for countersinking available; 60°, 82°, 90°, 100°
Single-flute for use when other styles of countersink chatter
used on small diameter holes where multiple flutes cannot fit