xkcd Phone 5

[Darkshado]

Features a buckling spring home button!

https://www.xkcd.com/1809/

[Wodan]

Membrane or capacative?

[Halvar]

I sometimes wonder if Randall Munroe reads DT.

https://www.xkcd.com/1806/

[andrewjoy]

That keycap profile on the home button , UHHHH!

[vivalarevolución]

That keycap profile on the home button , UHHHH!

I was going to say, that must be some kind of low profile buckling spring. Must be a Model M2 variety.

[just_add_coffee]

OP forgot to link to the group buy! Downvoted.