. I like the 9in. stock coil alot. Plan on a 6in. soon for the trashy areas etc. I also have this new 5x10 DD and I'm wondering if it is also a good coil for coin hunting? I'm getting good depth and ID with the stock coil on copper and silver but my nickel count seems to be only fair so far. Wondering if the the HF coil would help? Hope to hear back from you folks who have used the optional coils for coins and jewelry. Thanks Joe