You can distinguish between older and current versions of the Magnetic Field Sensor (MG-BTA) based on the appearance of the sensor.

-Black plastic shaft with a swiveling head and a white dot at the end of the tip
-Range switch on the shaft of the probe
-Began shipping in January 2006

-Clear plastic shaft with a white dot on the side
-Switch box on the cable with HI and LO ranges (these correspond to the 0.3 and 6.4 mT ranges of the current version sensor)

Magnetic Field Sensor Troubleshooting and FAQs