Actually used a $25 chinese unit three times to locate broken/rubbed/greenie in the harnesses of six month old Petes that had a design flaw in the harness routing,(imagine that) rubbed through on frame gusset..Guy at work pulled that thing out of his bottom drawer and smiled, said check this thing out..Of course I was skeptical but it actually worked..it emitted a little beep all the way down the harness till it passed the greenie then stopped..The problem is justifying hacking into a large brand new harness that's still under warranty,but when freight has to move..make it happen...I'm sure there are better more expensive units out there but, I acquired one of the cheap units and it worked on the latter two of those greenie issues...