Fit for clasping 7mm diameter cable. This rectangle Ferrite Bead can be widely used in a variety of Data cables, USB cable, telephone line, Network Line to Shield external electromagnetic interference. In order to ensure the safety, reliability and purity of data transmission. Helps reduce EMI on AC power lines. Black plastic enclosed ferrite core for 5mm AC power cords. Great for cutting noise on USB, Firewire, Phone, Power Cord, Coaxial, Audio, Video etc cables. Easy Structure and convenient installtion. Just clip it on and you will get clearer signal and faster data transmission. Â