This shield features the MSGEQ7 graphic equalizer display filter, the same IC used in the Colorganic Spectralizer kit. Two of these ICs allow you to split a stereo audio input into 7-bands (per channel) and read the amplitude of each using the ADC on your Arduino. The shield is populated with two 1/8" stereo jacks (like you would find on a pair of headphones). One serves as a stereo input and the other is a pass-through output which allows you to connect the Spectrum Shield in-line between your audio source and your stereo system without interruption. This shield can be used to create sound visualizers, detect patterns in music or add sound activation to your microcontroller projects. Project description, more information and ordering can be found at https://www.sparkfun.com/products/10306 Datasheet: https://www.sparkfun.com/datasheets/Components/General/MSGEQ7.pdfhttps://www.sparkfun.com/datasheets/Components/General/MSGEQ7.pdf Example Code: http://dlnmh9ip6v2uc.cloudfront.net/datasheets/Dev/Arduino/Shields/SpectrumAnalyzer2.zip