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

Current
-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

Older
-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)

RELATED TILs
Magnetic Field Sensor Troubleshooting and FAQs