T-Bone over on Raley's Small Engines made a good video on this game changing tool. I can find water pipes INSIDE my house walls. Places where there is no insulation. One dead cylinder on a twin mower engine. Hard starting issues quickly diagnosed. Many many more. Bad breakers or loose neutrals in your electrical panels....... Here's another one, dragging brake calipers on your car or truck. Low tire pressure found by excessive heat. Drafty cold air blowing in under your doors and windows.