Excal 1000, Excal II, Sovereign GT, CZ-20, Tiger Shark, Tejon, GTI 1500, Surfmaster Pulse, CZ6a, DFX, AT PRO, Fisher 1235, Surf PI Pro, 1280-X, many more because I enjoy learning them. New Garrett Ca
That depends on a lot of variables. Basicilly it is as deep as the coil is wide on a coin sized object that is laying flat and it is properly ground balanced.