I don't know whether my F 75 will go deeper, with the same coil, then a F 70, (I see no reason to think it will) but I have dug a couple of quarters with the stock DD coil at depths of 12-13". (measured) I had the opportunity, however, over the Thanksgiving day weekend to try a F 70 stock coil on my F 75 and the fellow with the F 70 used my 75 DD coil. Both coils were easily hitting the same targets in the 9-10" range, the deepest we came across. I got the sence, though, that the F 70 stock coil in moderate ground might go a little bit deeper then the 75 DD coil. I'm not sure however, there is enough difference between the two coils depth wise for a F 75 swinger to need the F 70 coil, but I do see the advantages of an F 70 user getting the F 75 DD coil. The DD does have better target separation and, of course, is better in more highly mineralized ground. Before I went out and bought either coil, though, depending on which detector one has, if you don't have the small coil, that would be the next coil I would get. Particularly, if one hunts trashy spots. That little sweetheart gets great depth and will eek out good targets that most other coils have and will miss. HH jim tn