The Garmin 12 GPS is a rugged 1990s 12 channel GPS. It uses four AA batteries. It is too old to include WAAS support so positional accuracy is conservatively ~5-10 meters.  It can store 500 waypoints, 1024 track log points, and nine proximity waypoints.

These positions can be downloaded to a computer as XYZ locations using the Garmin PC Interface Cable (RS232), the ARF has one of these cables.

For integrating Garmin data into ESRI GIS the simplest method is to use DNR Garmin (free) for Arcview 3.3 or ArcGIS 9.