Milwaukee MW500 PRO ORP Meter

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SKU: MW500
Accuracy: ±5 mV
Range: ±1000 mV


The Milwaukee MW500 PRO ORP meter is one of Milwaukee's most popular meters with its reliable, fast and simple operation as well as its accuracy.

The Milwaukee PRO ORP Meter is preferred by people looking to dial in their testing program when they have an ongoing need to maintain levels. Common uses are aquariums, swimming pools and spas, and other water quality monitoring uses.

When combine and used with MA924B/1, the PRO ORP meter can also be used to measure sulfur dioxide in wine using the manual Ripper titration method.

The Milwaukee PRO ORP meter offers:


The PRO ORP meter is accurate to ±5 mV exceeding the needs of most users.


The rugged meter is designed to take knocks.

Low maintenance

The PRO ORP Meter comes with SE300 ORP probe that is both low maintenance (gel filled) and able to withstand more challenging samples (double junction).

Design features

  • Fast easy to read current results with large digital LCD readout
  • Accurate to ±5 mV
  • Gel-filled, double junction lab grade Platinum ORP electrode for low maintenance and high performance
  • 3 feet probe cable for extra flexibility when testing
  • Low power demand for a 300 hour extended battery life (battery included)

Use and Care 

Properly maintaining your ORP probe will give you fast, accurate results for longer.

Here are our top three tips. 

1. Always store with the cap full of buffer or storage solution not water.

2. Clean your probe regularly by soaking in cleaning solution.

3. Check the probe using MA9020 200 - 275 mV solution to ensure the probe is good.



Thank you for considering Milwaukee to help you take your results to the next level.


  • mV Range: ±1000 mV
  • mV Resolution: 1 mV
  • mV Accuracy: ±5 mV
  • ORP Electrode: SE300 (included)
  • Environment: 0 to 50°C / 32 to 122°F; max RH 95%
  • Battery Type: 1 x 9V (included)
  • Battery Life: Approx. 300 hours of continuous use
  • Dimensions: 5.7 x 3.1 x 1.6 inches
  • Weight: 7.8 ounces (with battery)