No info about availability.
Specs are approved by the manufacturerRing modulator using vacuum tube in audio circuit.
Erica Fusion Ring modulator module uses pentode tube and it multiplies two signals to create unique waveforms rich in partials, bell like sounds, as well as tube distortion effects.
http://www.ericasynths.lv/en/shop/eurorack_modules/4550-fusion_ring_modulator.html
These merchants probably sell this module. Huh?
Erica Synths Fusion Ring Modulator V1
Erica Synths Fusion Ring Modulator V2
Erica Synths Fusion Ring Modulator V1
Erica Synths Fusion Ring Modulator V2
Erica Synths Fusion ringmodulator V2
Erica Synths Fusion Ring Mod v2