Bosch D-tect 120 vs GMS 120-27 (2026): Which Wall Scanner?
The Bosch D-tect 120 and GMS 120-27 are the two Bosch Professional wall scanners tradespeople compare most. Both find metal and live cables, but they work in different ways. Here is how D-tect 120 vs GMS 120 compares, and which one is worth buying for your work.
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Buy the D-tect 120 if you need to find plastic water pipes or scan masonry and concrete, as its radar finds every object type Bosch lists, including water-filled plastic pipes. Buy the GMS 120-27 if you mainly need a tough, simple detector for metal, live cables and timber, and do not need to find plastic pipes.
D-tect 120 vs GMS 120-27 at a Glance
| Feature | Bosch D-tect 120 | Bosch GMS 120-27 |
|---|---|---|
| Technology | Bosch patented radar | Metal, live wire and wood detection |
| Plastic pipes | Yes, water-filled plastic pipes | Not listed |
| Live and dead cables | Live and non-live cables | Live wires |
| Metal | Magnetic and non-magnetic | Shows magnetic or non-magnetic |
| Wall modes | Drywall, concrete and universal | Simplified mode selection |
| Toughness | Supplied with a protective bag | IP54, shock-absorbing rubber casing |
| Power | 4 x AA or a Bosch 12V battery via adapter | 2 x AA |
The Key Differences
What each one can find
This is the deciding factor. Bosch lists the D-tect 120’s radar as detecting all object types, including live and non-live cables, water-filled plastic pipes, and magnetic and non-magnetic metal. The GMS 120-27 is listed for metals, live wires and wooden substructures, and it tells you whether metal is magnetic or not, but plastic pipes are not on its list. If you drill near underfloor heating, plastic plumbing or in masonry walls, that gap matters.
Ease of use
The GMS 120-27 is built for quick checks: an LED ring around the centre marking hole turns red when it finds an object and green when it does not, with centre indication and material identification on the display. The D-tect 120 asks a little more of you, with drywall, concrete and universal modes, but adds a spot view that gives a result even when there is no room to slide the scanner along the wall.
Toughness and power
The GMS 120-27 is rated IP54 with a shock-absorbing rubber casing, and runs on two AA batteries. The D-tect 120 runs on four AA batteries or a Bosch 12V battery through the included adapter, which is handy if you already run Bosch 12V tools.
Bosch also makes the D-tect 200 C, which adds screenshots and a leak detection function, but at the time of writing it is listed on Amazon UK with a long dispatch time.
The Bosch Wall Scanners to Look At
1. Bosch Professional D-tect 120
Best for finding everything, including plastic pipesPatented radar that finds live and non-live cables, water-filled plastic pipes and magnetic and non-magnetic metal, with drywall, concrete and universal modes, spot view, and AA or 12V battery power. Supplied with batteries, adapter and a protective bag.
2. Bosch Professional GMS 120-27
Best everyday site detectorDetects metal, live wires and wooden substructures, shows whether metal is magnetic, and uses a red or green LED ring around the marking hole. IP54 with a shock-absorbing rubber casing, supplied with a pouch and two AA batteries.
Which Should You Buy?
- Plumbers, heating engineers and anyone drilling near plastic pipe: D-tect 120.
- Electricians and second-fix trades mainly avoiding cables and finding studs: GMS 120-27 is usually enough.
- Masonry and concrete walls: D-tect 120, which has a dedicated concrete mode.
- Comparing more scanners: see our best wall scanners guide, which also covers Zircon and Franklin.
Frequently Asked Questions
Is the D-tect 120 better than the GMS 120?
It finds more. The D-tect 120 uses radar and lists water-filled plastic pipes among the objects it detects, while the GMS 120-27 is listed for metal, live wires and wood. The GMS 120-27 is simpler, IP54 rated and built for quick site checks.
Can the Bosch GMS 120-27 detect plastic pipes?
Plastic pipes are not listed among the objects the GMS 120-27 detects. Bosch lists metal, live wires and wooden substructures. For plastic pipes, Bosch’s radar D-tect scanners are the ones that list them.
Does the D-tect 120 work on concrete?
Yes. Bosch lists three detection settings for the D-tect 120: drywall, concrete and a universal mode for when you do not know the wall material.
Can you trust a wall scanner completely?
No. A wall scanner reduces the risk but is not 100 percent reliable. Follow safe zone rules and isolate circuits where you can before drilling near cables.
Related Guides
- Best Wall Scanners UK
- Best Voltage Testers for Electricians UK
- Apprentice Plumber Tool List UK
- Black Friday 2026 Tool Deals for UK Tradespeople
As an Amazon Associate, TradeStack HQ earns from qualifying purchases. Some links on this page are affiliate links, we may earn a commission if you buy, at no extra cost to you. Product details are taken from manufacturer and Amazon UK listings as of October 2026.