Specially designed for drilling in hard steel,thick web helix delivers fast material removal combined with increased durability for maximum officiency and performance. Each bit is manufactured to exacting specifications and features a split point that starts on contact with no walking or skating,eliminating the need for a center punch. There is deviation between metric(mm) and english(inch), be aware before ordering.Product Details: Diameter:  3/8 inch Flute length: 3.19 inch Total length: 4.92 inch Material: 5% Cobalt Package: Plastic box Drilling Reference: Material: Automobile leaf spring steel plate Drilling Speed(r/min): 450 Feed rate(mm/r): 4 Drilling depth: 10mm Holes: 2HSS M35 Cobalt Twist Drill Bits, Pack of 5 (9.5mm, 3/8")