3-in-1 Multi-functions: It can help detect invisible objects: wood or metal Studs up to 1.5", live AC wires up to 2" and Metals up to 2.36". Avoid drilling into water pipes and wires hidden within the walls, help doing some DIY in a safely manner.
Use the thumb button to calibrate away from the material to be detected, before use.
An video of the tool here :
MANUAL HERE:
https://www.scribd.com/document/421083567/TH231-Instructions-Millx-Stud