Galvanized case hardened steel self-tapping thread inserts with internal and external thread. Ideal for producing metric screw threads that are capable of supporting heavy loads. Vibration and wear resistant. Suitable for materials with low shear strength such as aluminium alloys, brass, bronze, cast iron, Duroplast and thermoplastic resins. The thread inserts have a cutting slot and a tapered bottom, which allows them to join together. When screwed in, they cut their own threads inside the hole, ensuring that it is fastened firmly and securely.