Ryobi SW109TL Stud Sensor

Measures distance and volume with pin-point accuracy.
Locates wood, metal and wiring in dry lined stud walls.
Measures distances using the speed of sound and laser pointer for accuracy.
Adds up continuous lengths for skirting boards, dado rails, picture rails etc.
Stud sensor measurement: wood/metal up to 38 mm (1 1/2in) dry wall with centre accuracy up to +/- 12.5 mm (1/2in).
Ultrasonic measurement: 60 cm - 15 metre (2ft - 50ft).
Ultrasonic accuracy: +/- 0.5%, 0-1 digit.
Auto beep stud detection: Yes.
Auto shut-off: Yes.
Battery: 9V.
2-year warranty.