· We Shan Dong PT International Trade Co., Ltd is a professional manufacturer of steel balls, with a total investment of over 30 million, covering over 7,000 square feet, to produce stainless steel ball (440c, 304,316 L, 420,430),. Can provide you with a variety of specifications of the ball in the G10-1000 level range of the ball,we company has advanced production equipment, improve the detection equipment, through its high-end equipment on the ball: roundness testing, vibration testing, the value Testing, surface quality testing, Rockwell hardness testing,we big family sincerely wish can make cooperation with you to become more higher,more stronger together!!!