From company website: "The StudSensor HD55 stud finder is a popular, mid-range choice among DIYers and professionals alike. Featuring the functionality of the HD35, it additionally introduces an enhanced LCD display with Target Spotlight and a second scan mode. Now, choose to find the edges of wood and metal studs through one layer of drywall or through two layers with the additional DeepScan mode. WireWarning Detection alerts users to live, unshielded AC wiring for added safety, promoting confidence in every project."