22 pcs ferrite core bead choke ring set with multiple inner diameters: 5mm, 5mm, 7mm, and 9mm. Antiinterference design The nickel zinc ferrite material clamps onto cables to reduce electromagnetic interference and enhance signal stability, contributing to smoother device performance. Wide compatibility and applications Suitable for car DVRs, headsets, speakers, keyboards, USB cables, audio cables, power cords, and other electronic wiring harnesses that may benefit from noise suppression. Easy installation Snap the rings onto your cables to improve current stability and sound quality without tools or special expertise. Use scenarios In a vehicle: suppress EMI on dash cam power and data cables to help prevent noise and video artifacts. On a computer desk: reduce interference on USB peripherals, audio cables, or keyboard/wired mouse connections for clearer signals. In home audio or home theater: clean up wiring for speakers or other audio equipment to enhance signal integrity.