Save your money. No matter what coil you put on it, it won't go much deeper if any. You have to change the power output to go deeper and you can't do that. If you want deeper you are going to have to get a PI detector. Whites makes several. If its a larger target you are seeking, a 2 Box will go to 6', but won't pick up anything smaller than a softball. Whites made a Sierra Madre/ULA-3 with a 15" coil that would go about 5'. it sold for app. $600. Dream on, Frank... I already used up 2 wishes, there is only one left.