ce577368_ight_For_The_Ground_Conditions__Double_D_Coils
Motion and Coverage [Monoloop Coils] Closer to the coil the detection coverage is right around the coil perimeter. This means more coverage pushing the coil forward under shrubs and bushes than a DD. [Double D Coils] 
Has a wedge shaped detecting profile which is better swung from side to side. If you push it forward and back under vegetation you may miss some gold.
Metal Detector Coils Get Them Right For The Ground Conditions
Double D Coils