Negative Positive
Title: Dean
Review: Tested it by putting behind my vehicle's muffler while my car was running. Tested all 4 I bought and only 1 of the 4 I bought went off. I tried test it a second time a few hours later and 2nd time none of them went off with no reading. I returned it to Amazon and bought the Kidde KN-COPP-B-LS 900-0230 tested the 3 I bought with same method and all past with flying colors.
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