Rockfshr, I'm ashamed that I'm a little overextended time wise to look up the owners manual on the Explorer to read about the iron mask feature, but I own a Quatro. It's one great machine, goes very deep, probably as deep or almost as the Explorer, it has one numeric readout versus two on the Explorer, but don't let that scare you too much, because if you look into it, it's pretty intuitive as far as reading both ferrous and conductive and coming up with a very accurate numeric as well as audio reading on that. It also has the "notch discrimintation", which allows you to "knotch out" specific numeriec readings, which corrispond to the type of target or metal that your detecting, so you can literally discriminate against a particular type of metal or pop top, or whatever, very specifically. You can get on the Mlinelab website and download the owners manual for any of their machines and read about whatever you want to, as well as the iron mask. I. Hope you get an answer on your questions. I love the Quatro. It has amazing depth, discrimination of all types of metals, and also is second to none on avoiding problems related with mineralized ground. I never have, or e x t r e m l e y, seldom have any problems with salt water or black sand at the beach. The only thing that plagues me at all is gettin wet, salty sand between the coil and coil cover and all you have to do there is take the cover off or clean out the crud now and then and your good to go. Hope that helps you. Marc.
