Franklin Sensors ProSensor, a hidden structure finder. With as many as 9 sensors, it will find a post or beam very accurately. No complicated settings or calibrations. Just press a button and guide it along the wall, and it doesn't matter where you start - even right from the post, it will still show you correctly. Now, about what it can find. Shows not just, and will indicate both the center and the edges at the same time: single posts, double, even some non-standard configurations - all as in the palm of your hand. Works through drywall. It can detect the presence of live wiring. It runs on regular AAA batteries and is not compatible with rechargeable batteries. It makes any repair a fun adventure, not a headache.