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Pocket CO 300 - Carbon Monoxide Detector
Pocket CO 300 Package Pocket CO 300 Front-Back Pocket CO 300 with Keys

Pocket CO 300 - Carbon Monoxide Detector

The most innovative carbon monoxide detector/alarm on the market today, the Pocket CO 300 brings together effective carbon monoxide detection and warnings with easy portability and an affordable price. The Pocket CO is especially well-suited for pilots looking for a carbon monoxide detector that will outperform those "sticker" detectors while taking up a bare minimum amount of panel or cockpit space. With it's ability to be worn or attached to a keychain, the Pocket CO 300 can easily travel with you between your aircraft, boat, car and home with little-to-no fuss. The Pocket CO 300 alerts you to the presence of CO using an 82dB audible buzzer, LED light, and case vibration to ensure you don't miss the warning.

Product Features

  • Compact and Lightweight - can be worn or attached to keychain
  • 3 alarm methods - 82dB Buzzer, LED light, vibration
  • Two Modes of Operation - 12hr detection and Continuous Detection
  • Runs on a single CR2450 coin cell battery you can replace yourself
  • Perfect for space-conscious aviators, truck drivers or home owners
  • Made in the USA with a 1 year manufacturer warranty
SKU Pocket CO
Weight 0.50 lbs
Market price: $139.99

The World's Smallest and Most Innovative CO Detector/Alarm
The Pocket CO 300 is designed to be a simple and effective way to determine, measure, and even record Carbon Monoxide (CO) levels in any environment. As a stand-alone unit in a compact size, the Pocket CO 300 can be carried on a key ring, clipped to your clothing or attached to an instrument panel. It's been specifically designed to be affordable and fit the needs of vehicle operators, health professionals, and concerned homeowners alike. You won't find a more portable, economic solution that still provides you with effective carbon monoxide detection and alerting anywhere else!

Simple, Quick Activation and Operation
The Pocket CO 300 offers to modes of Operation. "12hr" and "Continuous" monitoring allow you to determine how long the unit samples the ambient air to alert you of CO dangers. Here is how these modes differ:

Mode of Operation Display Shows Sample Interval Time Period
12 Hour (One Push of Button) "12HR" Every 5 seconds 12 hours then auto off
Continuous (Two Pushes of Button) "ON" Every 5 seconds Indefinite until turned off by user or battery expiration
Upon activating the unit, a self test of the circuitry, alarms, battery and operating temperature is performed to ensure the unit is performing up to spec. The Pocket CO 300 has 3 different alarm levels to alert you to the presence of carbon monoxide:
Alarm Levels Alarm Interval
50 - 124 PPM alerts every 20 seconds
125 - 399 PPM alerts every 10 seconds
400+ PPM alerts every 5 seconds

The Pocket CO 300 versus the CO Experts 2010
While we feel that both the Pocket CO 300 and the CO Experts are great tools for detecting carbon monoxide, they each have their own pros and cons. The Pocket CO 300 is ideally suited for pilots or other customers looking for a super-portable carbon monoxide detector that can go with them anywhere. This is the biggest selling point of the Pocket CO - it's portability. The cost is also attractive to those customers looking for a solid carbon monoxide alarm on a tighter budget. However, the Pocket CO 300 does have some important bits of information that should be taken into account. First, the manufacturer of the Pocket CO does recommend yearly calibration of the device with an inexpensive home calibration kit. Also, the accuracy of the unit is affected somewhat by altitude - down to 70% at 10,000 feet MSL. It should be noted that this decrease in it's ability to read is not of great concern because this reduction in performance is mainly centered around the unit's ability to detect low-levels of carbon monoxide. Altitude should not greatly affect the unit's ability to detect and alert you on dangerous levels of carbon monoxide that might require immediate action. In our experience, we've not been able to see a significant difference in reaction time over other gaseous diffusion units when it comes to CO levels over 25ppm. Also, the Pocket CO 300 requires user action to begin screening for CO. This is easily done on the unit as described above, but it does contrast with the CO Experts which will continuously detect the presence of CO as long as the battery is present and still putting out a charge. Finally, the warranty that is available on the Pocket CO is one year versus the CO Experts which is 5 years.

The CO Experts, with it's larger chemical sensor, is certainly the better performer of the two units, but comes with it's own set of obstacles. First and foremost, the CO Experts is much bigger (about the size of an average smoke detector) and space-conscious pilots or other customers may have difficulty finding a mounting location for it. Secondly, it is not as portable as the Pocket CO and, while still being easy to transport between locations, it isn't as simple as attaching it to a keychain like you can with the Pocket CO.

In the end, both the Pocket CO and the CO Experts are fantastic units. Deciding which one to go with really is a matter of your budget and space concerns. If you are looking for something very portable, the Pocket CO 300 is probably the unit for you. If you are looking for a top-performer with a longer warranty and the best performance on the market, give the CO Experts a try.

Display Readings Indicate:

  • Total exposure (ppm-hrs)
  • Time weighted average TWA (ppm)
  • Max Concentration (ppm)
  • Time of occurrence of max concentration (hrs/min from start) length of collection



2.4 x.1.4 x.0.6 inches


Less than 1 ounce, 20 grams


0-500 ppm CO


+/- 10% of reading at standard conditions

Response time:

<90 seconds to 90%

Warm-up time:

2 seconds

Operating life:

1-year minimum

Operating temperature:

32-105 F, 0-40 C displayed; readings automatically compensated

Pressure effect:

Reading decreases with decreasing pressure, down to 70% at 10,000 ft.

Humidity limits:


15-85% RH, non-condensing

(Visual and audio):

CO above the 25 ppm OSHA TWA and >125ppm
   and >400 ppm ceiling value.
Temperature above 122 F (HOT),
Temperature below 32 F (COLD)
Low Battery "BATT". Dead Battery "----"
Not calibrated/tamper "CAL"

Sampling mode:

Gaseous diffusion



None significant, except hydrogen


Battery, alarm, display, temperature, tamper

Service life:

Two year (warranted).  Can be extended by replacement of battery and sensor.   Pocket CO is warranted to operate on average 8 hours per day and 5 days per week for one year with no replacement of sensor or battery. Pocket CO will last longer with reduced usage.  For example if you use it twice a week for a few hours in flight it may last 2 -3 years.


For most applications, 90% accuracy is acceptable and no maintenance is required. On startup, if the self check fails or low battery appears on the display, factory maintenance is required

Low levels of CO, typically less than 10 ppm, are not considered especially hazardous, but they do indicate a source of CO. Sustained levels above 25 ppm for 1.5 hours, and exposure to more than 70 ppm CO should be avoided. Seek clean air, ventilation, or any other means to eliminate exposure.


Ordinary UL-approved residential CO detectors -- the kind you find at Wal-Mart or Home Depot -- simply won't do for such critical applications. And those chemical spot detectors sold for auto and aircraft use are basically useless. Here's why.

To be UL-approved for residential use in the United States, CO detectors are not permitted to be very sensitive. UL requires that they must not display CO levels less than 30 parts per million (PPM). Furthermore, they must not alarm unless exposed to 70 PPM for four hours, 150 PPM for 35 minutes, or 400 PPM for 15 minutes! These requirements were imposed by UL at the request of gas utilities and firefighters to minimize the number of unnecessary emergency 911 call-outs from homeowners. (Yet most fire departments require that firefighters put on their oxygen masks if CO levels are 35 PPM or higher ... go figure!)

For use in aircraft, boats, RVs and other critical environments, however, we believe that a far more sensitive detector is essential -- one capable of displaying and alarming at far lower concentrations of CO. After all, you're not simply concerned about protecting the health of the occupants, but also about preventing cognitive impairment of the pilot or driver. In addition, low levels of CO can be extremely hazardous in aircraft because the effects of CO and of altitude (hypoxia) are cumulative.

How much CO is too much?

It depends on whom you ask: 

  • The EPA (U.S. Environmental Protection Agency) calls for a health hazard alert when the outdoor concentration of CO rises above 9 PPM for eight hours, or above 35 PPM for one hour.
  • The OSHA (U.S. Occupational Safety and Health Administration) originally established a maximum safe limit for exposure to CO in the workplace of 35 PPM, then later raised it to 50 PPM under pressure from industry.
  • The FAA now requires no more than 50 PPM during certification testing of new general aviation aircraft (FAR Part 23), but older aircraft were certified with no CO testing, and the FAA requires no regular re-testing of aircraft during maintenance (although we think it certainly should).
  • Underwriter's Laboratories specifies that residential CO detectors must not alarm below 70 PPM, and then only after that concentration has been detected for four consecutive hours.
  • Yet most fire departments require that firefighters put on their oxygen masks if CO levels are 35 PPM or higher.
  • Many doctors believe that long-term exposure to CO levels as low as 10 PPM can lead to cognitive and physical problems, particularly for infants, children, pregnant women, and the elderly.

We consider CO concentrations of 10 PPM or more in an airplane cockpit to be significant, and concentrations of 35 PPM or more to be grounds for declaring an emergency, going on supplemental oxygen (if available), and making an immediate precautionary landing.

By the way, those el-cheapo chemical spot detectors sold for aviation and motor vehicle use are basically worthless -- they require prolonged exposure to 100 PPM or more before they darken to provide a warning, and by the time that occurs, you might well feel too ill to notice. The UL-2034-compliant residential CO detectors you'll find at Wal-Mart and Home Depot are a little better, but not much.

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