Most natural gas detectors detect methane (natural gas) and propane. Portable “sniffer” models may detect a wider range of organic vapors and fuels — for example: acetone, acetylene, alcohol, ammonia, benzene, butane, ethanol, hydrogen, naphtha, paint thinner, solvent, gasoline, and hexane.

Typical inclusions are a user manual, a protective case, and charging cables (micro‑USB) for rechargeable sniffers. Some models also ship with a packaged 9‑volt battery for backup. Note that many plug‑in units list only the detector and the manual.

Common options include plug‑in/AC outlet models, hardwired alarms, portable rechargeable handheld sniffers, and units with battery backup (either rechargeable or replaceable batteries).

Common features are loud audible alarms, visual alerts (LEDs or backlit displays), one‑touch silence/test buttons, and digital displays that show current and sometimes peak readings.

They appear as handheld portable sniffers with flexible gooseneck probes, plug‑in/AC outlet units, and combo alarms available as hardwired or plug‑in room monitors.

Listings recommend placement near potential fuel sources and appliances such as behind dryers, stoves, fireplaces, grills, or water heaters. Some plug‑in and portable models are also described as suitable for outdoor use, like camping or RV trips.

Some models combine gas detection with carbon monoxide, smoke, temperature, and humidity sensors.

Only one listing specifies an electrochemical CO sensor; other descriptions mention CO detection but do not name the sensor technology.