Have many kinds of usb cable on the market, but the key is to see how the customer to choose? What need to pay attention to details, to choose good quality cable. Usb cable quality and specification description: 1, the quality of wire rod specifications: appearance model with lettering Usb, 4 core round wire, sheath material: PVC45P, material shape: circular, the tensile strength: P, wire and maximum overall diameter: 3. 5 ( mm） , minimum 2. 0 ( mm) , the thickness of insulation: 0. 2 ( mm） , product certification, ISO9001. Softness, feel is good. Description: color: black some conclusions: 4 core, 2 core, bare copper, more than twisted categories: aluminum foil shield, or a chalk line, USB head round line 2: USB head material; There is a rubber core, copper, iron shell; ( a) Look iron shell material nickel plating, the plating is good, will not rust, no corrosive and destructive gases. ( b) Injection use PVC environmental protection rubber 60 p appearance, luster is bright surface, no shrinkage, blister and deformation etc. Bad phenomenon.