I'm John Bidwell, inventor of the "water-cooled spark gap", and this is the more affordable ES Series (Experimenters Series).

Purchase one of the world's first commercial water-cooled spark gaps - this starter kit comes with a "WCSG Mini", tri-electrode, experimental bowl electrode, an electrode form tool, a high voltage decal and an "ES Series" card signed and numbered by their inventor (me). This listing is for 'production number 2' in this continual series.

You can find the complete manual for this WCSG-Mini, plus other helpful online resources at my website: WCSG-Science.com

Thank you and happy experimenting!