|Should not be confused with manual valves, even though they look (almost) totally the same.|
This is the central part of a Toxins bomb: to use it, load it with two gas tanks and a trigger (which can be, for example, a signaller or a voice analyzer). When the trigger is activated, the two gas tanks will mix, usually creating a large explosion if loaded with the right mix. To remove gas tanks or the trigger from it, use it in your hand; it's important to do it when you want to disarm it.
A finished bomb: