Made of Tool Steel- Machined for a perfect size cavity for carbide insert seat, Hardened & Precisely Ground Supplied with a TNMG16 ( 3 face x 2 sides cutting edge) which is replaceable as soon as this is worn out. Just screw a new one, and your tool is new and good to go again. Shanks are precisely machined to square and then ground. Size of the shank and carbide insert reference, is etched for user's easy reference. Designed specially for our large head 4" fly cutting tool. However this can be fitted to any other flying tool that can accept a 1/2" tooling.