This is the Maxon CP-101 compressor effector. It's an early model, a vintage large box with a caramel switch. It has scratches and dirt from use, but it works well. Feel free to ask if you have any questions! The MAXON CP-101 provides a clear compression effect thanks to its wide dynamic range and design with ample maximum sensitivity. It features sustain and level controls, allowing for everything from long sustain effects with deep compression to limiter effects with shallow settings. The balanced compression effect during chord cutting and the clear, extended sound during lead work are unique to MAXON, and it's also effective for bass.