They last for 5 years and then you're supposed to replace them. Since I'm still alive, it must have done it's job, so I just replaced it with the same model that was there.
Just paste this into Amazon:
MTI Industries 35-742-WT Safe T Alert 35 Series Dual LP/CO Alarm - Flush Mount, White
Pat & Karen
2021 Grand Design Solitude 310GK
2020 Ford F350 Lariat, Crew Cab, Short Bed, Diesel, 4WD
Retired and trying to travel where it's warm. Not doing a good job of this during COVID in 2020.