... steel,Alloy steel,Copper,Aluminum are available.Carton steel is high quality iron,such as 1022,1018,1010,1008,1015...Medium ... as :Self tapping threads "A","AB", Threads for chipboard screw,wood screw,drywall screw;Type "M","UNC","UNF","BSW"threads for Machine threads.Head ... other company,but is reasonable for products,it will spend high control force from material till products reach in customer hands ...