As many users of the Kruzer series may find the 4 tone mode really limited because it is so noisy and hard to follow. I personally rarely notch out targets and even keep my iron audio low but always audible but there are some really tough spots. In particular spots like camp sites or where there were bonfires and lots of burned up can slag, bottle caps etc. I took the 4 tone mode and notched out everything except known or metal ranges of known target id types. I then use under the iron audi