Hey Craz8
Go to Zircon.com look for the M40 watch the video
I have used 1 for over a yr. now 2" on a coin 4" on metal.
Zircon makes stud finders for the home they are shaped bad but the M40 is great for a pinpointer.
Any home improvement store can order 1 for you ,i got mine a lowes for $30 bucks runs a 1 9volt batt. still haven`t changed the batt.yet built very well.
Gary