USB Cat 5e/6 Balun, 12 Mbps Device End, USB-B Male. A USB balun is a deceptively simple gadget that quietly solves headaches in many professional AV setups including, but not limited to, extending USB peripherals beyond spec limits, conference rooms and corporate AV setups, live production and event spaces, KVM extension, digital signage and interactive kiosks, education and training environments, surveillance and security integration, and much more.