This will block incoming cable TV channels 75-80, allowing the Media Center Modulator or Component Modulator to broadcast an in-house "security" or "entertainment" channel over the coaxial cable system without interference. Simply couple to the coaxial cable TV input on either a splitter or an active video distribution device such as Leviton 3x8 Bi-Directional Video Module (#47690-38B) . Makes room in your channel array for any home security or entertainment video application. It also blocks outgoing signals, such as cameras, from being broadcast outside the home.