4/0TINNED COPPER WIRE ferrule car audio amplifier amp inputINNER DIAMETER OF METAL FERRULE IS .550INNER DIAMETER OF RED housing is .700QTY: 10 PCS WIRE SOLD SEPARATE IN OUR EBAY STORE Product Name : Vinyl Insulated Wire FerrulesMaterial of Body : Copper , Tin PlatedMaterial of Insulation : VinylColor of Insulation : red