New answers tagged fire-sprinkler
I was in total agreement with Ecnerwal, that those bumps were to hold it in wall board. Finding this picture tells a different story: (notice the bumps and the threaded insert) My best guess is that up in the ceiling somewhere, is the rest of the part; those bumps thread into it, or you can just push (see, 4.a). Be gentle with it, those are 50 bucks. ...
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