The Commander 15x12 is a great coil, If you have room to swing it.
IMEO Nugget Finder is a better choice then Coiltek Goldstalkers. the NF is fully potted, wound with litz wire and waterproof to 2 meters and has a longer warranty and costs less.
The Goldstalkers by Coiltek the windings are held on a foam blank with masking tape this becomes loose with age and is very prone to false signals.
here is a video I made demonstrating the stability of NF coils, try that with a goldstalker!
http://www.youtube.com/watch?v=GVWEFO2C-rM
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