M3 x 0.50 Coarse Thread DIN 985 Class 8 Nyloc (Nylon Insert Locknut) Standard Medium Carbon Steel Black Oxide Pk 2500: Amazon.com: Industrial & Scientific
Amazon.com: MonsterBolts - M5 Nylon Insert Lock Nuts, DIN 985, Alloy Steel, Black Oxide, 10 Pack : Industrial & Scientific
Carbon Steel Lock Nut, Zinc Plated Finish, Right Hand Threads, Self-Locking/Nylon Insert, Meets DIN 985, M4-0.70 Threads (Pack of 100): Amazon.com: Industrial & Scientific