All good info above. To expand on Florida son's comment about the test garden, if you don't have one ( I do not) I always bring common modern coins and worn,dug coins that you would expect maybe hiding (mercs, barbers, Indian heads, large cents ) so that you can scatter them on the old property and note their audio and tid in various settings as the coil passes over them. This can also aid in improving pinpointing over the coins (seeing where the loudest sound(sweet spot) is acquired on a specific section of the coil, without having to cut a plug. Oh yeah, and the same goes with trash, pop-tops, beaver tails, bottle caps, can slaw if you choose to bring them with you. Some users reject them in their own personal settings. HH