I know this is marked as answered, but i thought i'd reference this, as we've had a lot of customers coming to us asking for information on how these keycaps work and fit. Here is a guide we've made on how to replace the keycaps on the butterfly clip type ranges. (this includes the 12" MacBook ranges as well, despite them having an older butterfly clip design)
https://thebookyard.wordpress.com/2018/05/04/macbook-pro-retina-2016-and-2017-keycaps/