Built on the foundation of popular 4x4s, the 4x4 PRO USB SERIES Power Distribution System from ART is designed to provide reliable power for many applications. It provides the surge protection you need to keep your rack safe from unwanted disruption. It also has an internal discrete module called APF (Advanced Power Filtering), which filters out digital and dimmer hash as well as any high-frequency noise that is above the audio range. Some off-the-shelf add-on modules saturate and lose their filtering effectiveness as the load increases, but by using a high power discrete design, this 4x4 is able to provide filtering that stays effective over the full operating range.