Variable tooth unique variable tooth geometry for consistent cutting ability in a wide range of materials Manufactured to strict Alpha specifications to suit demanding Australian conditions 8% cobalt Bi-metal gives ultimate performance and superior welding technology prevents tooth strippage 38mm cutting depth Recommended Speeds Mild Steel 285 Cast Iron 190 Tool Steel Stainless 145 Brass 380 Aluminium 425 Wood 2400 Recommended for use with a small arbor .