Locate the edges of studs or joists through drywall and other common wall materials with the Stanley Tools Stud Sensor, which works at a maximum depth of 3/4". It emits electronic audio and visual signals once the edge of the stud is detected. Automatic shut-off provides longer battery life. It even includes a pencil notch for marking stud edges. Requires 1 9V battery, not included. Measures approximately 8-7/8"H x 4"W x 1-1/8"D. Made in China. Home Improvement,Tools,More