... tools 55 SiMoVA(AISI S2) ball , this product mainly used for oil drill, drill ore in parts. Size: Φ 6mm-28mmChemical ... as 55 SiMoVA roller and ball, this product mainly used for oil drill; and drill bits parts,stamping parts, plastic ... , stainless steel, copper and all kinds of different line fasteners, cylindrical pin, Under well-trained workers, consummate production facilities, advanced processing ...