A4 MARINE GRADE STAINLESS STEEL NYLOC NUTS. PLEASE SELECT FROM DROP DOWN MENU. Nylon insert nuts are an economical means of combatting loosening from vibration. A nylon neck situated at the top of the nut, is slightly narrower than the thread; as the nut is tightened, the nylon grips the corresponding thread. A2 stainless steel material, offering superb resistance to corrosion. M4 X 0.7 PITCH. Listing and template services provided by inkFrog.