Stays sharper longer. Variable Helix flute geometry for faster material removal. Chip breaker decreases heat build-up. Set includes one 1/8 in (3.2 mm) with chip breaker, one 5/32 in (4 mm) with chip breaker, one 3/16 in (4.8 mm) with chip breaker and one 1/4 in (6.4 mm) with chip breaker.