For more than 20 years, America's leading companies have trusted Tripp Lite's Isobar Premium surge and noise suppressors to protect sensitive computer, networking and telecom equipment. With more than 14 million satisfied customers, the Isobar remains the world's #1 selling premium surge suppressor. Loaded with a generous combination of high quality components, near indestructible all-metal case and unique noise filtration system, the isobar offers the highest level of protection attainable in a multi-outlet strip. Robust surge suppression circuits with sine-wave tracking offer extreme levels of protection against the heaviest surge conditions exceeding IEEE 587 category A & B specifications. Isobar's unique protection system combines large torroidal chokes, ferrite rod-core inductors, HF/VHF capacitors and multiple layers of metal oxide varistors into exclusive isolated filter banks that remove EMI/RFI interference, even noise generated by other pieces of connected equipment. ISOBAR4/220 offers 4 outlets arranged in two filter banks to prevent system crashes, reboots and performance problems common as noisy system peripherals are powered off and on. Surge suppression rated at 330 joules offers network-grade protection. Widely spaced NEMA5-15 outlets accommodate up to 2 large transformer plugs without blocking outlets. Includes 1.8 meter AC line cord and keyhole mounting tabs.