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Our low cost, full featured, easy to use and deploy NetGuards are our latest Temperature Guard offering.

Two models available to operate in either wired (M308) or wireless (M309) Ethernet networks.


They are designed to simply and easily monitor a refrigerator/freezer storing temperature sensitive drugs and samples at a very competitive price.


Designed to Meet All VFC Requirements

  • Monitor two temperatures from -328°F to 392°F

  • Ambient temperature and humidity sensor included

  • Calibrated measuring range: -149°F to 78°F with +- 1°F accuracy

  • Available with optional NIST certificate
  • Displays current, Min, Max temperature readings

  • Internal alarm buzzer (85dB) actively notifies out-of-range temperatures

  • Low battery indicator

  • 4000 readings memory storage

  • User programmable logging interval

  • Comes with free software to download log file, send alarm emails/text messages.

Apps available for Android and iOS

Ethernet NetGuard

(M308 shown)M

Feel free to call us if you need more information. 

M308 (wired Ethernet): $355

M308 with NIST calibration certificate: $395

M309 (wireless Ethernet): $375

M309 with NIST calibration certificate: $415.00

Optional Alarm relay output: $20

(Order alarm relay if you will be connecting to alarm system)

Temperature sensors are not included.  Available sensors can be seen here.





The M308/M309 share identical specifications.  The only difference is which type of Ethernet network they operate on.  The M308 operates on a wired network, the M309 operates on the wireless (wifi) network.


The M308/M309 can monitor two temperature sensors and two door inputs, which is perfect for a fridge/freezer combo unit.

Runs for up to six hours without power on its internal rechargeable batteries, continuously logging data in its internal memory.

Stores up to five months worth of data on the M308's internal memory.

Stores 180 days of daily Hi-Lo temperature data for each sensor.


Download the temperature log file via our free Data Capture software.


Our free PC based Data Capture software simplifies your temperature recording tasks by automatically recording the temperature status of all of your M308/M309 units across your entire network. Data Capture also sends out alarm emails and text messages when a sensor goes out of limits.


  • Onboard storage records 4000 temperature readings

  • 180 days of daily Hi-Lo temperature readings for each sensor

  • Local audible alarm

  • Optional relay output for connecting to an existing security system or strobe

  • Programmable high and low limits for each sensor

  • Programmable alarm time delay for each refrigerator/freezer

  • Data Logging capabilities


  • Maximum temperature sensor range: -328°F to 392°F, -200°C to 200°C

  • Factory calibrated range -149°F to 78°F (-100°C to 21°C) to better than 1°F degree

  • Field calibration can be performed at one point

  • Measurement resolution 0.1°

  • Sensor Type: 1000 Ohm Platinum (.00385 TCR)

  • Number of Temperature Inputs: 2

  • Number of Door Sensor Inputs: 2

  • Internal Memory:  4000 records

  • Internal Memory Data Update Rate: Programmable 1 to 60 minutes

  • Internal alarm buzzer

  • Rechargeable battery backup included keeps the M308 operating for up to 2 days (except for network connection).

  • Internationally compatible plug-in wall transformer included (100-240v 50-60hz) Standard US plug.

  • Operating Temperature Range 32°F to 125°F

  • Enclosure Dimensions: 5.625" x 3.250" x 1.375"


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