A type of equalizer pedal developed by Boss/Roland Corporation. Oftentimes labeled as the SP-1, it's an equalizer pedal with one band, with that being the spectrum, and it also ranges from 500Hz to 5kHz. The Balance controls the stability of the Spectrum. They are oftentimes found on eBay, and yes, unfortunately, they are extremely expensive, too.
Guy 1: Have you ever tried that Spectrum EQ?
Guy 2: Not really, but I have heard about it.
Guy 1: If you do find one, be careful. It's very expensive.
Guy 2: Thanks for the heads up. You do the same.