1.made with 9CrSi,D2,HSS, M2, 440b, 440c, etc 2.tolerance within 0.002mm 3.OEM for customer 4.more than 20 years experience ... points a knife, the most important link, its processing precision, more demanding, for plane, our factory is made of super precision ... grinding machine plane, with special grinding method, grinding and become, and the strict quality ...