... , UNI, BS, JIS, ISO, DIN ASTM A194 hex heavy nuts: Our company are specilized in the manufacture of different ... kinds of standard hex nuts for many years, including standards of ISO, DIN, ... 1" Class/Grade:class4,6,8,10. grade2,5,8. Head Mark: "S" S 8 , S10, S 181 etc. ... meantime our customer head mark (just say " N 181, N 161, N 2H") ...