The THREE.1 is AudioControl's in-dash car audio processor that combines a four band stereo EQ along with a 4 channel, 2-way electronic crossover. This �one box solution� is a great car audio processor for enthusiasts who want the sonic benefits of AudioControl components but have limited installation space.The THREE.1 starts with four stereo equalization controls including a Para-Bass control to give subwoofers an extra kick. It also features a 4 channel, 2-way, 24 dB/octave car audio crossover with a fader. To round out the package the THREE.1 also includes a subwoofer level control, speaker level inputs, master volume control, and selectable illumination color. AudioControl's line of in-dash car processors offer features and functions that allow you to adjust and tweak your performance car audio system from the convenience of the driver seat. Included are features like equalization, electronic crossovers, master volume control, high voltage line drivers, and speaker level inputs.