The Firlarm Plug-in CO Detector does one thing and does it well: it tells you exactly how much carbon monoxide is in the air. The digital display shows real-time PPM readings, so you’re not waiting for an alarm to know something’s wrong. That matters because CO is odorless and colorless—by the time you feel symptoms, levels can already be dangerous.

The sensor triggers an 85dB alarm and flashing red light when CO hits 150ppm. That’s loud enough to wake you from sleep, and the visual cue helps if you’re in a noisy room or have hearing difficulties. It plugs directly into a standard AC outlet, which means no batteries to swap and no wall-wart taking up space. The white casing is unobtrusive—it blends into most rooms without looking like a piece of safety equipment.

One thing to note: this is a plug-in unit, so placement is limited by outlet location. It won’t work in rooms without accessible AC power, and you’ll want to keep it away from high-humidity areas like bathrooms to prevent false alarms. For the price, it’s a straightforward, no-fuss addition to any bedroom or hallway where you need reliable CO monitoring.