As you indicated, Phase Lock matches the detector's GB setting to the phase value, analyzed at a given time. And, that phase value changes with every movement of the coil. It is affected by the distance the coil is from the ground, the mineralization of the soil and any targets in the vicinitiy. After using mine for several hours today, I've found that the phase value never remains steady. And, can vary as little as 4 or 5 "numbers", to as much as 30 or 40 "numbers" or more, within one sweep. It just depends on what is being analyzed by the coil at any given time. I'm not saying this is a bad thing. But until this "on the fly" phase value indication was available, all we could tell about how well our detector was GB'ed was to check it periodically and make the necessary adjustments. Either that or run in a tracking mode. With the F5, watching the phase value change and making every effort to keep the detector balanced becomes the "new challenge". It is no different than other manual GB detectors. It is just that with the F5 you can actually see how much the phase relationship varies as you sweep the coil over varying soil conditions and targets. And that might make some folks nervous! Understanding how much variation you can "tolerate" before it effects your hunt, is going to be key to maximizing the detectors performance. And frankly, I've not used mine long enough to figure that out yet. JMHO HH Randy