I bought a stud sensor years ago that had 304 4 led's that ramp up as you get to the center of the stud. One day out on a job I needed it and found I'd left it at home. I was far enough from home that I had to buy one from a local lumberyard (2x normal price) that was by the same manufacturer, but new and improved (where have I heard that?) It only had two LEDs and was OK. Later I was wowed at Home Depot by the Zircon TriScanner Pro that has 3 levels of scanning, AC detection, etc.
I've never had great results with the TriScanner pro and found myself going back to the "new, improved" model instead.
Working at the house recently I pulled out the original Zircon stud finder and found its 4 leds to be more precise and accurate. I went out to the truck and got the new improved one and the "Pro" and have decided the original one is the best. That's in the truck now, with the TriScanner Pro (it looks snazzy but don't get much use).
I find them pretty indespensible.
Anyone figure out how to make the TriScanner Pro useful? Get it near AC and it's useless....
=Tom