alot depends on the makes and models --whats the differance between a ford and a caddy? their both cars right?---same differance---often older coins (pre 1964 for silver --pre 1932 gold) tend to be deeper due to when they were lost---the older "shallow" detectors and cheaper modern models may not find some of these deeper coins ---lacking the "depth" needed ---some folks pay big bucks in hopes that their "caddy" type detector will find these deeper coins for them ---the 3 and 15 tend to be the deepest going bands --by it can vary depending on many factors--soil and menerails be just two of them--Ivan