This device will locate metal pipes, voltage carrying cables (AC voltage) and wooden studs in walls. It gives you three very useful functions in one appliance, with individual switching between each one. It features a large LCD (numerical and bar chart) as well as an audible signal. The sensitivity is automatically controlled for best performance. To save battery power the unit has an automatic switch-off function. Powered by a 9V battery (not supplied). This is a very user friendly easily operated and accurate detector.