As we have already determined, the fermentation process involves yeast converting sugar into alcohol with the simultaneous release of carbon dioxide. An essential condition for the normal course of fermentation is the absence of oxygen access to the mash. If oxygen enters the vessel with fermenting mash, the alcohol will undergo a chemical oxidation reaction with oxygen. As a result, the mash will break down into acetic acid and water. Instead of a quality mash, you will end up with something incomprehensible. This "incomprehensible" substance will have a strong vinegar smell and a low ethanol content. Moreover, tightly sealing the vessel with the mash is also not an option—physics still applies, and you risk a local Armageddon in the form of an explosion, with the mash flooding the room from floor to ceiling. The ideal solution to remove excess carbon dioxide and prevent oxygen from entering the mash is a hydrolock.
In summary, regardless of the variety of options, the principle of operation of a hydrolock is to ensure the unhindered release of carbon dioxide from the vessel with the mash and prevent the entry of fresh oxygen. Therefore, it is not so important which specific design to choose—the main thing is that it successfully copes with these two tasks.
Additionally, you can purchase hydrolock plugs here.