The tabs broke when I rushed to turn off the smoke detector, so I made this copy using a caliper and printed a new one. Fits on a Nexa model 13314/KD-134A with 91 mm base diameter.

I dont know if this is a common dimension and if it will fit on other smoke detectors as well.

The onshape design can be copied here: https://cad.onshape.com/documents/e399d92efb0c760b85f1c02f/w/77799775a18fbb5f4661b6ee/e/d9bca470ce7128f79187976a?renderMode=0&uiState=65b9520f6da5e638caa980e9