We set up a professional technical team with the cooperation of research institutions, colleges, and universities. For instance, chinese academy of sciences are our direct cooperator, professor mr bern klein university of british columbia, canada is one of our team members. 1.Material: b2, b3, bu 2.Surface hardness: hrc58-65hrc, volume hardness hrc56-63. 3.The impact toughness of our grinding balls is more than 18 j / cm2. 4.The actual broken rate