I don't know - I have a small roughly 15x15 area in my back yard. I went over it countless times from countless angles with the safari with pro coil. I did find a 1907 barber quarter, a couple of indian heads, and several wheaties. not bad safari. but that was the first few times over it. i went over it again and again after that and thought i had pretty much picked the area dry. ran the etrac over it (which i just traded in the safari for)- crisp 12-43 signal and out pops 1916 merc at about 6 inches - then another crisp 12-43 signal in same area and out pops a 1946 roosevelt at about 5 inches. I also used the pro coil with the etrac. factory settings auto plus 3. safari missed them - high trash area. etrac better with dimes? smaller silver? i don't know - just found it interesting.