I'd also like to hear more of an explanation... I bought an electronic leak detector around 5 years ago. I've used it to find/fix leaks in A/C systems (mobile and stationary units) at least 10 times. The one I have is incredibly sensitive and, to date, it has never failed to find the leakage point in a system I've been troubleshooting. I consider it one of the most effective tools in my tool chest.