Left hand spiral flute, right hand cutting. Manufactured to BS 328-4. | | METRIC TOLERANCES (to H7): | Diameter: ~ up to 3.00. Tolerance: High +0.008, Low -0.004. | Diameter: Over 3.00 ~ up to 6.00. Tolerance: High +0.010, Low -0.005. | Diameter: Over 6.00 ~ up to 10.00. Tolerance: High +0.012, Low -0.006. | Diameter: Over 10.00 ~ up to 18.00. Tolerance: High +0.015, Low -0.008.