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Milwaukee MA921B/2 Lab Grade Double Junction ORP Platinum Probe

SKU: 9139-MA921B.2~ea

SKU: 9139-MA921B.2~ea

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Milwaukee MA921B/2 Lab Grade Double Junction ORP Platinum Probe with Extended Cable

The Milwaukee Double Junction ORP Platinum Electrode is specifically designed for the continuous analysis of aquariums and is meant to be used with Milwaukee Monitors and Controllers.

The resin body is highly durable, chemically resistant and protects against accidental breakage of the sensing bulb.  It is gel-filled which removes the need to maintain electrolyte levels.  The double junction design reduces the risk of clogging which leads to more stable ORP measurement and reduced maintenance.


  • Body: Glass
  • Reference: Single, Ag/AgCl
  • Junction: Ceramic, triple
  • Electrolyte: 3.5M KCl+AgCl
  • Range: 0-12 pH
  • Tip Shape: Conic
  • Diameter: 0.5 inches
  • Dimensions: 4.7 inches / 6.4 inches
  • Operating Temperature: 23 to 86°F)
  • Cable length: 3.3 feet
  • Connection: BNC


Properly maintaining the ORP probe will provide fast, accurate results for longer.  Here are tips to keep the probe working properly:

  1. Always store with the cap full of buffer or storage solution, not water.
  2. Clean the probe regularly by soaking it in cleaning solution.
  3. Calibrate after cleaning and/or storage before testing to adjust for changes in the ORP probe sensor