BTW - Ground Notch is not TID Notch. It looks like some folks are confused by this based on the responses. Ground notch is an expert GB setting that allows you to set a range over which hot rocks and other ground feature targets that have a ground phase reading significantly different than the surrounding ground will be ignored to prevent hot rock falsing. You set it based on the ground phase reading range you expect to see at the site you are searching. It has nothing to do with notching out specific TIDs like pull tabs or zincs (that is a separate traditional notch feature and setting that has nothing to do with ground notch), so no one is going to miss any gold because of it. Some folks have indicated that it might have some effect on being able to discern deep targets. Since the telltale signal that hot rocks and coke/coal at a site can often be recognized and committed to muscle memory after you have dug few, I find no need to risk a depth hit or other downside that comes from invoking yet another "hidden" filter (like silencer) in my programs, so I just don't bother with it. HTH.