M12 Hexagon Lock ( Half ) Nuts Stainless Steel A4(316) DIN 439

A4 half lock nuts are used in a variety of applications, such as machinery, furniture, and plumbing, especially where space is limited or a secondary locking action is needed. They function by being tightened against a primary nut to lock it in place, or they can be used alone as a "jam nut" when a full-size nut is too thick for the application. Their A4 stainless steel composition makes them resistant to corrosion.