Smallest and
Multi Gas Monitor

Portable multi gas monitor

Smallest and Lightest
in the world

Best solution

for your
for your
for your


OSHA safety

For the

Comparison with other

Compared to other companies' products, the GX-3R and GX-3R Pro are small and lightweight.
Therefore, it is a very easy-to-use product that does not get in the way of work.

Comparison with other companies

Breathing zone

Some workers think detectors come with a wide detection range. OSHA in U.S., though, defines the breathing zone as, “a hemisphere forward of the shoulders within a radius of approximately six to nine inches.”

For the

Sensor Technology

Because the sensor was also developed in-house, the GX-3R and GX-3R Pro were designed with an intimate understanding of the sensor characteristics. This enabled us to succeed in developing a compact, high-performance sensor.

  • HC or CH4

    Tough construction against poisoning-and impact-resistant!

    HC or CH4
  • O2

    New electrochemical oxygen sensor,which improved the basic characteristics.

  • CO & H2S

    2-in-1 configuration enabled smaller detector!

    CO & H2S
  • CO

    Significantly reduce H₂ interference with a two-sensor structure!

  • CO2

    Ultracompact & lightweight infrared sensor

  • CO/H2S/SO2/HCN/NO2/PH3/NH3

    Improved basic characteristics! Toxic gas sensors

    CO H2S SO2

High quality R-sensors

GX-3R and GX-3R PRO mounted with the new R sensor series, which have dramatically improved the performance from the previous sensors.

11 features
Partly only for GX-3R Pro

  • Usable in Harsh environment

    Usable in Harsh

  • Water proof equivalent to IP68

    Water proof
    equivalent to IP68

  • 7m drop resistant

    7m drop

  • Connectivity


  • Long life

    Long life

  • Lighter & Smaller than smart phones

    Lighter &
    Smaller than
    smart phones

  • Standard sensor warranty for
3 years

    Standard sensor
    warranty for
    3 years

  • Various certificate approval


  • 3 step alarm points

    3 step alarm

  • Various certificate approbal

    Possible to switch
    the combustible
    gas on display

  • CO sensor with less interference from hydrogen

    CO sensor with
    less interference
    from hydrogen

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Supports 16 languages

Supports 16 different languages for smooth operation.
* Supported languages ​​differ depending on specifications.

For the

Docking station SDM-3R

Allows the user to perform a simpllfied pre-work check(bump test) and gas calibration automatically.

More Details
safety matters

RK LINK Overview (free option)

The GX-3R Pro can communicate with smartphone and tablets via Blutooth. Allows alarm to be issued to remote location in real time to notify emergency situations using the dedicated RK Link app. Also allows the main unit's setting to be altered.
Download the free RK Link app from Google Play or Apple Store.

RK LINK Overview (free option)

Connectivity with other devices

GX-3R Pro can be connected to various devices.
The following are examples of development based on requests from customers.


The TR-L1 is a converter that converts Bluetooth signals into LoRa signals. It was developed in response to a request from a Korean customer who wanted to use LoRa. The TR-L1 also has an additional GPS function, enabling the user's current location to be ascertained, in addition to GX-3R usage.
Please contact us for details.

Connectivity with other devices

* LoRa is capable of communicating over hundreds of meter in unobstructed outdoor conditions.


The GX-3R PRO, provided by our subsidiary RKI Instruments, can also be connected to the Guardhat Platform. Guardhat is a platform that detects, warns and prevents industrial accidents. The system collects information in conjunction with sensors such as gas detectors and radiation detectors used in the field, detects and warns of dangerous industrial incidents, and helps to prevent accidents. Please contact us for details.

Product details

World‘s smallest and lightest
Multi Gas Monitor

Portable Gas Monitor

  • - World's smallest and lightest 4 gas monitor
  • - 3-year warranty
  • - Only Approx. 100g
  • - Water and dust resistant, IP66/68
  • - Loud alarm buzzer 95dB at 30cm
More Details

High end model
[ Bluetooth, Various sensor line up ]

Portable Gas Monitor

GX-3R Pro
GX-3R Pro
  • - World's smallest and lightest 5 gas monitor
  • - 3-year warranty
  • - Compatible with 11 languages
  • - Connect with Bluetooth
  • - Water and dust resistant, IP66/68
  • - Loud alarm buzzer 95dB at 30cm
More Details

Support Options

Pump unit RP-3R(Pro)
  • - The product is designed to be attached to the GX-3R/GX-3R Pro Portable Gas Monitor (available separately) to draw in gas using the built-in pump.
  • - The RP-3R(s) can be connected to the GX-3R.
  • - The RP-3R(Pro/S) can be connected to the GX-3R Pro.
More Details
Docking station SDM-3R
Docking station SDM-3R
  • - Model name: SDM-3R
  • - Power supply (AC adapter): AC100–240V ±10% 50/60Hz
  • - Suction flow / intake rate (approx.): 0.25L/min.
  • - Operating temperature and humidity range: 0–40°C (no sudden changes), max. 95%RH (no condensation)
  • - External dimensions (approx.): 130 (W) x 110 (H) x 250 (D)mm Weight (approx.): 800g
  • - Optional accessories (sold separately): connectors, wall mount fittings, exhaust tube
More Details

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Customer reviews


About us

Since our company was founded in 1939 under the umbrella conglomerate of RIKEN, our management philosophy has been to create safe working environments. Our science and technology research laboratories have developed industrial gas detection warning devices, specializing in monitoring harmful gases in the work environment, as well as for explosion prevention from combustible gases. Without compromise, we continue to challenge ourselves to be technological leaders, developing and manufacturing a wide range of industrial gas detection systems and monitors. From large-scale gas detecting alarm systems to small-sized personal gas monitors for safety protection; used in many industries including semiconductor and LCD plants, petroleum complexes, steelworks, various tankers, oil storage stations, underground gas facilities, and volcanoes.

image for over 80 years

Experts in gas detection for over 80 years

The “RIKEN Gas Detector” utilizing the principle of light wave interference, was exhibited at the 1937 Paris World Exposition. Its subsequent use greatly contributed to the prevention of accidents in coal mines where many fatalities were prevalent at the time. On the 15th March 2019 we celebrated our 80th anniversary. Supported by our history and tradition we shall further improve long established technology, and continue to innovative. Developing reliable quality products in response to the diverse needs of industry.

Extensive international network
for reliable and complete support

Utilizing our established overseas network, you could purchase
our product and services all over the world.