440 stainless steel ball bearing 1,ABEC7 2,High speed 3,End cover:ZZ,RS 4,Noise level:Z1,Z2 ... excellent property of high temperature resistance.Thanks to these advantages,the products are widely used in medical mechanism,chemical industry mechanism ... , 17% Cr, .5% MoA hardened , martensitic stainless steel, 440C is the standard choice for a wide range of military and commercial applications. 440C ...