Now I see what you all mean about using small coils. I had the F4 with the 4" coil yesterday and detected very close to the poles on the swings and found several coins. At the end of my hunt I had 40 coins and 12 of them were quarters. My wife used it for awhile and found 2 pieces of cheap quality jewelry. If anyone with a F4 is thinking about getting the small coil for it - I say go for it, it is a great combination. Steve.