The RH-03 Stereo Magnetic Field Sensor is a simple 9v powered circuit that uses two inductors to sense electromagnetic fields. The PCB is custom designed, hand-wired and soldered, and mounted inside the hardwood case (available in a variety of different wood choices).
It's a great noisemaker, especially when paired with a stereo resonator, vocoder, or similar effects unit. Wave it around electronic devices such as transformers, leds, cell phones, computers, or other devices to get a variety of different sonic textures.
It connects to any audio equipment via a 3.5mm stereo jack.