Ferrule, Polypropylene (Sleeve) , Tin Plated Copper (Tube) MaterialInsure reliable electrical connections and prevent fraying and breaking of wire strands when terminating conductors in screw clamp terminal blocks. Insulated ferrules have molded-on plastic sleeves and prevent conductor breakage due to bending, wire stress or vibration. Dual wire insulated ferrules provide reliable connection of multiple wires into the same terminal block clamp and simplify jumping between terminal blocks. All ferrules are packaged in 100-piece standard packs. - Sleeve: Polypropylene. - Tube: Tin-plated copper.Insulated ferrules prevent conductor breakage due to bending, wire stress or vibration while facilitating wire insertion into the terminal clamp.