Set of 2, no connector included.
Device:
Dimensions: 15.5 mm inner diameter (flexible), 20 mm outer diameter (max)
Outputs: 1 channel per ring
Rated power: 1-5W (See inductor specs)
Compatibility:
Can be plugged into anything: amplifier, audio DAC, signal generator… Check inductor specs (link in DIY section).
DIY:
https://github.com/AxelFougues/Lodestone-biomagnet-tools/wiki/Wired-Rings