I currently use a Tesoro Cibola as my main detector but am in the process of trying to pick out another machine. The F-19 appears to be what I would like to have but after some research I got a question or 2. If I understand what I have been reading, which I may not understand at all, the Khz is what is used for depth and the ability to find smaller targets, if that is the case why is 19 khz about as many as you can find on anything and why are some detectors very popular and use less than 19khz? I am not stuck on getting a Fisher, I have had one in the past and liked it, but I have had Garretts and Tesoro's and have used a Whites. But if the F-19 is a depth machine I would like one. I would like to see what lays deeper on the places I have detected. Thanks for any info...d2