What are the operational limitations of my Stanley Fatmax Stud Sensor?

Operates on panels up to .75” (19mm) or 1.5" (38mm) thick for metal studs, and drywall up to 2" (50.8mm) thickness for AC wire detection from a distance of 6"-18" (.15m - .5m). Ensure smooth surface within temp range 32°F to 122°F (0°C to 50°C). (Page 17)