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Bosch GMS120-27 Wall Scanner and Stud Finder, Detects Wood, Metal, and Live Wires Behind Your Wall - Includes 2 AA Batteries and Pouch

TLDR Review: Bosch GMS120-27 Wall Scanner

Item: Bosch GMS120-27 Wall Scanner
Author: ShopSavvy

By ShopSavvy Team

Published: February 1st, 2026

Pros

•Detects steel studs up to 4.75 inches deep, wood studs up to 1.5 inches, and live wires up to 2 inches behind walls, offering strong depth range for various materials.
•Works reliably on thick drywall, plaster, plasteoated walls, and wood paneling where many other stud finders fail.
•Useriendly interface with simple modes for wood, metal, and live wire detection, plus automatic calibration and clear sound and visual alerts.
•Builn marking hole allows precise pencil marking directly through the tool, eliminating guesswork for stud or pipe location.
•Backlit screen helps with visibility in dim environments.
•Includes 2 AA batteries and a soft carrying pouch, so it’s ready to use right out of the box.
•Shocbsorbing rubber casing and an IP54 rating provide good durability for tough jobsite conditions.
•Offers peace of mind when hanging heavy items by reliably locating studs and plumbing pipes.
•Smooth gliding across surfaces enhances ease of use.
•Performs better on challenging wall materials compared to many budget competitors.

Cons

•Has difficulty consistently detecting live electrical wires, especially behind standard halnch or 5/8-inch drywall, limiting safety reliability.
•Sometimes produces false positives, especially on walls with unusual materials or multiple signals, which can be frustrating.
•Metal detection often only finds drywall nails, providing little advantage over a simple magnet tool in some cases.
•LCD screen can be hard to read from certain angles, requiring awkward positioning to get a clear view.
•Selalibration occasionally does not improve detection accuracy or reliability.
•Performance varies depending on wall composition, making it less dependable for all professional applications.
•Some users find the tool fiddly and inconsistent in stud and wire detection.
•Overall wire detection range and reliability are limited compared to expectations at this price point.
•Not always as accurate or trustworthy as more expensive or professionarade stud finders.

Bottom Line

The Bosch GMS120-27 Wall Scanner is a solid all-around stud finder that excels at detecting wood and metal studs deep behind a variety of wall materials while offering durable construction and useful features like audible alerts and a marking hole. However, if consistent live wire detection is a priority, this model struggles with reliability and may leave you wanting more. For those needing enhanced electrical wire detection or more professional-grade precision, considering higher-end alternatives or specialized wire detectors may be wise. Overall, it’s a dependable choice for general stud and metal scanning jobs but not the top pick for detailed electrical safety needs.