440C Stainless Steel Sphere, Grade G25, Mirror-Like Finish, A276/ A756/AMS 5630, 1mm Diameter, 0.0006mm Sphericity (Pack of 250) 440C stainless steel is wear resistant and can be heat treated to very high hardness ratings, surpassing the hardness of 440A and 440B stainless steel Mirror-like finish provides a bright, reflective appearance Meets A276, A756, and AMS 5630 specifications Grade 25 Standard tolerance