In case you were wondering how removable cores work.
On the left is a zip valve extender, and on the right is a core removed.
The idea is that you take out the core, put the extender in its place, and then put the core into the extender. Just don’t toss out at tube with an extender, thats a sad day since they are about $15 on their own :(.
There is another kind of extension that just screws in on top of the core, but I really don’t like them. The reason why is that you have to release the twist on the valve like you are going to pump it up, and then fit the extension. If you mess it up, you could have to change a tire. Thats a bad day if you are pumping up before your race :/