... -M12material: steelzinc plated: colorful , white and blue ,blacktype: body with open notch, head with notchwe use cold forged technique, not only save materials ... , round body, hex body, open end, closed end, body with ribben, body with groove and so on . also we can produce according ... ,5/16,3/8 . material: steel, stainless steel, brass,aluminium notch plus nut