Someone on here referred to them as "scrivets" as in Screw-Rivets, which essentially is what they are. When removing these, use a Philips head, but do not apply any pressure on them or they will just spin. When reinstalling them, don't try to tighten them down too much either. They only have to go down until they are flush with the surround. You don't tighten them like screws. When they are all the way down, they expand the plastic flares beneath, like a rivet.