⭕ GEOMETRICS G-856 Portable Proton Magnetometer System with MagMap2000 and MacPick data software. The entire system is in excellent condition! The G-­856 provides a reliable, low cost solution for a variety of magnetic search and mapping applications. Single key stroke operation means the G-­856AX can be operated by non-technical field personnel or used in teaching environments. The G-­856AX uses the well proven proton precession technology, allowing accurate measurements to be made with virtually no dependence upon variables such as sensor orientation, temperature, or location. The unit provides a repeatable absolute total field magnetic reading.