This is a “toilet flapper.” It is the name for a real thing. Like any name, it can be used in sentences. “I had to purchase a new toilet flapper.” I went to the hardware store to purchase a universal toilet flapper.” I successfully installed the new toilet flapper.” “The new toilet flapper is excellent.”
I like that the name is a description.
The whole DIY/repair thing has some interesting philosophical extensions that go beyond Heidegger on broken tools, you might like this essay and there is a reading/audio of it in the comment section:
https://deterritorialinvestigations.wordpress.com/2016/08/01/lauren-berlants-the-commons-infrastructures-for-troubling-times/