Very few things impress me as much as this did. It has taken a clever idea to the next level of simplicity. I was expecting something similar to the one AvE took apart, but this one is completely different. I'm not sure if the cells are custom made or if they are standard zinc air cells, but the way they've been used is extraordinary. Do standard zinc air cells liberate gas when discharged slowly without a ready source of oxygen? A search for suitable keywords brought up a patent:- https://patents.google.com/patent/US5242565A/en A notable excerpt from that is the following:- "U.S. Pat. Nos. 4,105,830 to Kordesch and 4,189,526 to Cretzmeyer both describe "air depolarized" oxygen consuming "zinc air cells" but do not describe cells for the "evolution" of gases. Due to the teaching of the present invention it would be hindsight from the description of these cells to conclude that these cells contrary to their disclosures may be used as "hydrogen evolving cells" by simultaneously excluding oxygen from their cathodes and forcing electric currents to flow through the cells." In this case the oxygen exclusion may be simply leaving the storage labels that block the air vents in place (You activate zinc-air cells by removing the label.), and the forced current may be a simple resistor across the cell. I specifically avoid using intrusive mid-run video adverts, which means I don't earn as much from my content as other YouTubers. If you enjoy these videos you can help support the channel with a dollar or two for coffee, cookies and random gadgets for disassembly at:- https://www.patreon.com/bigclive Patreon supporters get early access to advert-free videos as they are made, and also regular live streams. This also keeps the channel independent of YouTube's advertising algorithms allowing it to be a bit more dangerous and naughty. Other contribution options are available at:- http://www.bigclive.com/coffee.htm #ElectronicsCreators