This is for a aftermarket car keyless entry and remote start control that has been discontinued. It is 7mm long, 2mm wide, and the button is about 3mm long. It has to placement pegs on the bottom and looks like 4 contact points. I can’t find any thing similar. In the pictures it is the buttons on the side that are a white body with a silver front. The are 3 of them but I only need to replace one.
If it's not the exact same one, look through the same manufacturers other versions; it's a rarer style with the switch contacts at the back rather than the sides.