OSD Audio ISS4 4-Channel High Power Stereo Speaker Selector Switch with Impedance Matching Protection EXPAND YOUR AUDIO ZONES: An easy solution for delivering audio from a receiver or amp to four pairs of speakers within a home or office environment EASY TO INSTALL: Accepts up to 14-gauge cable and includes European-style input/output connectors that are removeable for better leverage than old-style spring-loaded terminals SWITCHING FLEXIBILITY: Play any pair, a combination of pairs, or all pairs simultaneously, and dual-source switching lets you choose between two audio sources DURABLE BUILD: Quality you can feel right out of the box, circuitry is encased within a 16-gauge steel, not plastic, enclosure that includes a durable black powder coating IMPEDANCE MATCHING PROTECTION: Includes selectable impedance matching protection circuitry that allows a single amplifier or receiver to safely power several pairs of speakers without risk of damage