Overview Introducing ART’s 4×4 PRO USB SERIES Power Distribution Systems. Built on the popular 4x4 base, the PRO USB SERIES are reliable, durable-built power conditioners for use in many applications. Wherever a power management system is required, the USB 4×4 PRO SERIES provides the surge protection you need to protect your rack from unwanted disturbances. All PRO USB SERIES models have an additional internal discrete module called APF™ (Advanced Power Filtering) which filters digital hash and dimmer as well as any high frequency noise above the audio range. Some commercial add-ons saturate and lose their filtering effectiveness as the load increases, but by using a high-power discrete design, we were able to create a filter that remains effective throughout the entire operating range. Key Features Designed with a power capacity of 1800 watts APF surge/spike protection with EMI and RFI filtering Front-mounted unswitched power jack and adjustable rear gooseneck light source for bright illumination behind the rack . Rear socket spacing and alignment to accommodate different sized power plugs and AC adapters