Pat, I bought a 2200d when they first came out. A great detector. Been swinging mine for years, got nine pieces for 26 grams in the last two days. I use a booster with mine and they work really well with either the Koss 30`s or 80`s as Doc said. I recently bought a set of Black Widows from Rob, mainly for working on wide open windy salt lakes here in West Australia. I have tried a range of coils on mine and my coil of choice is the Wallaby 17'' x 11" DD. Most of my patch in West Oz is wide open and flat, so plenty of room to swing a bigger coil. I see by one of your replies you are planning two long trips. I would not drive down to the end of my street to run the 2200 without a booster. Do yourself a favour, "add on" a booster before you leave. And when you get a nice very soft sweet target, disconnect the booster and try the signal without it. I`m sure you will think "that was money well spent" ..... The standard 6v battery will serve you well. I changed to 7.3v lead acid battey a long time ago and now run 7.4v li-ion lightweights. You got a good machine!...........learn to listen to what it is saying to you. Good Luck on the two trips and may the Goddess of Plenty look kindly upon you. Driller.