Aerotight M24 A2 Grade Stainless Steel Self-Locking Nut Thread Pitch - 3.0 mm All metal Stiff nut with no inserts Can be re-used Will stay in position whether tightened down or not No special tools required When assembled on the screw, 2 full threads should protrude through the nut A2 stainless steel has good resistance to corrosion except in severe industrial and Marine Condition. Use A4 in a marine environment.