It will show on a metal detector. The battery on the 650 has the carabiner attachment which stayed connected to my wife. This is the screen/ button part of the unit (the valuable part).
she lost it in the top field from Blacks/ Smoothing Iron Ranch - across the road from the parking signage, etc... and up the farm road to the right to sit on a draw of opening modern deer. it is in that field somewhere - or was ;-)
thanks,
john