AudioQuest USB-A Noise-Stopper Caps shield unused USB ports from electromagnetic interference and radio frequency noise that can degrade audio performance. This four-piece set installs effortlessly over idle USB-A connectors, creating a protective barrier against RFI and EMI contamination while simultaneously guarding against dust accumulation and oxidative corrosion. An essential accessory for maintaining signal purity in digital audio systems and computer-based playback environments.