All the pins are clearly labeled.The case employs the metal(zinc alloy) material,anti-pressure; anti-interference; anti-high temperature. FLEXBILITY: The terminal block is more durable than soldering wires onto a connector. Can extend the length of the USB cable, ideal for you electronic DIY projects and test the equipment that with USB interface ports. EASY to USE: No soldering required. Just use a small screwdriver to open up the terminal blocks, slide in your stranded or solid-core wire, and re-tighten. Save you from solder trouble, no need to purchase expensive tool. Great time and money saver. DURABLE: Nickel-plated interface, anti-friction, strong oxidation resistance, effectively reduce resistance. The signal is more stable and has a longer service life. WIDELY APPLICATIONS: Suitable for U disk, keyboard, mouse, camera, printer, mobile phone and other devices with USB interface. Terminal blocks make it easy to test electronics equipment or power up.