NorthernMich is right !
I have had a Troy Shadow II (by Tesoro) for some years now, after having owned various brands over the last 40 years.
Just turn on and go...and with it's very powerful miniaturized circuit, one little, common, square 9v battery will give longer life than many others with a whole batch of batteries..
However; I have not been avidly into the THing for the last 5 years or so..things may have changed a bit.