lock nut 1)material: steel 2)grade: 4.8, 6.8, 8.8, etc 3)Surface: zinc plated 4)size: Dia within M12. 1)material: SS-304,SS-201,brass ,etc2)grade: 4.8, 6.8, 8.8, etc3)Surface: black,plain ,zinc plated,yellow blue zinc plated, etc4)size: GB,DIN,JIS & Nonstandard...(Dia within M12) lock nut