The 2 3/8" machinist file Blade has been tempered so that it has optimal toughness and edge holding properties. These blades are not brittle since they have been tempered. Machinist files are made to cut other metals they will even cut other files. So these knives have the very best steel you can get. The handle is of tough red acrylic with brass pins and a thong hole. The finger shape gives a very firm grip when working with slippery materials.