I believe it's custom, because the mechanical part is actually just part of a sensor (it's just a magnet in a slider). The other part is the hall effect sensor

I believe it's custom, because the mechanical part is actually just part of a sensor (it's just a magnet in a slider). The other part is the hall effect sensor which is soldered on the board. So, you can't drop these mechanical parts on to another board, they aren't self contained switches.