Review on Enhanced Safety: Sensorcon Industrial CO Carbon Monoxide Monitor - Visual, Audible, and Vibrating Alerts, Waterproof by Timothy Kiley

I use this when I work on my car, travel with AirBNB, hotels and long-distance travel. I always leave it on and carry it in my backpack. I take it out of my backpack when I'm working in the garage or somewhere that doesn't have other carbon monoxide detectors (like my house). Even in my backpack it warns you when you start the car in the garage and let it run for a few minutes. In a backpack, of course, it's not as effective, but it's not useless either. The clip can be removed with a screw.