Three Instruments Across Two A2 Models
Every Groundtech A2 Series unit carries two instruments. The 3D ground scanner uses the MFS-3 dual gradiometer sensor with a plus or minus 3000 µT range, which Groundtech rates at up to 20 meters, to map buried metal, magnetic objects and voids such as tunnels and rooms. The pulse-induction metal detector runs at 1 kHz for searching and separating ferrous from non-ferrous metal in the upper soil layers; Groundtech publishes no depth figure for it. The A2 has six modes: 3D Ground Scanning, Live Scanning, Pinpointer, Detector Quick Scan, Detector Advanced Scan and 3D Detector Scanning.
The A2 GEO adds a third instrument, the geo-electric resistivity system, and two more modes, Resistivity Automatic Scanning and Resistivity Manual Scanning. Groundtech lists its output as 100 V, 66 mA at 62 Hz with a 50 sample interval, and says it detects groundwater, tunnels, tombs and caves from much deeper levels. Groundtech gives no depth figure for the resistivity system. Resistivity results are analyzed in the Groundtech Suite application.
Who the A2 GEO Is For
The Groundtech A2 GEO is for surveys where the question is about the ground itself: is there water, a cave, a tunnel or a chamber, and roughly where. The resistivity system uses four conductive probes on 25-meter cables, and Groundtech says it scans across four lines in automatic or manual mode. Setting out probes and cables takes more time on site than walking a magnetic scan.
Our recommendation: if your targets are metal, caches or relics, the plain A2 does that job, and the geo-electric kit adds cost, weight in the bag and setup time you will not use. Choose the A2 GEO when locating water or deep voids is part of the work, not a maybe.
What Comes in the Box and What Fits
Groundtech's box list for the A2 is the main unit with its built-in screen, the MFS-3 dual sensor, the PiD25 and PiD30 detector coils, a headset, a charging adapter, a carrying bag and the user manual. The A2 GEO box adds the four conductive probes and four 25-meter conductor cables. Groundtech gives a 2-year warranty on both.
Groundtech does not publish the PiD25 and PiD30 coil sizes or list any optional coils or other accessories for the A2 Series, so use the two coils in the box. Groundtech also publishes no water-resistance rating. Both units run on a 3.7 V lithium-ion battery that charges over USB Type-C with support for a 25 W adapter; Groundtech rates about 10 hours in scanning modes (and resistivity on the A2 GEO) and about 6 hours in detector mode. For the last few inches of recovery, see Groundtech pinpointers.
Screen and Software
A Groundtech A2 Series unit runs standalone: settings, modes and scan graphics show on the built-in color screen, so no phone is needed in the field. Over Bluetooth 4.2 BLE, the G-Portal app for Android and iOS saves scans and shows them in 3D, with depth calculation and target shape. The A2 GEO also uses the Groundtech Suite application for resistivity data.
When the GR-4 Series Is the Better Buy
The Groundtech GR-4 Series costs less and covers a lot of the same ground. The GR-4 DUAL also combines a 3D scanner and a 1 kHz pulse-induction detector with a built-in screen, with one PiD35 coil and the MFS-2 sensor, which Groundtech rates at up to 15 meters. Pay for an A2 when the extra rated depth of the MFS-3 sensor, the second coil and the headset matter to you, or when you need the A2 GEO's resistivity system. For a first scanner on a budget, the phone-based Groundtech GR-3 Series is the lowest-cost Groundtech scanner.
Planning an A2 Series Survey
An A2 Series survey usually starts with the deep scan and narrows down from there. The 3D scan marks where something large or hollow sits, the pulse-induction detector with the PiD25 or PiD30 coil checks the spot near the surface, and on an A2 GEO the resistivity lines come out when the question is water or a deep void. Groundtech's 20-meter rating is for the magnetic scan only and varies with soil structure, object size and scan function; large objects and voids are what reach it, small items do not. Our page on how deep metal detectors go puts that figure in context, and metal detector technologies explained covers how the pulse-induction side works. Survey work on any land needs the owner's permission; our metal detecting laws and ethics page is a starting point.
Groundtech's lineup page showed the A2 Series and A2-GEO Series as current in October 2026.
