Contact J. R. Overseas company

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44 Lexington Avenue
Gloucester, MA, 01930


J. R. Overseas is a US company (Gloucester, Massachusetts) offering worldwide the finest in marine moisture and corrosion meters.  Our customers include safe-boating enthusiasts such as boat owners, boat manufacturers, marinas, boat yards, boat brokers and marine surveyors.

Order Accessories Parts and Manuals

Accessories, replacement parts and a corrosion manual can be found here.

Calibration Block

Calibration Block1.jpeg
Calibration Block1.jpeg

Calibration Block


This replacement item works with the GRP-33 Meter. Copper plated calibration block ensures accurate calibration.  Keep your GRP-33 calibrated using this block and a screwdriver.

How to use.

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