ce577368_ight_For_The_Ground_Conditions__Double_D_Coils
Ground Coverage [Monoloop Coils] Cone Shaped detection area - larger coverage at coil face which tapers off at depth Essential you overlap detector sweeps or you will miss gold at depth. [Double D Coils] 
Greater ground coverage per sweep. Will not penetrate as deep as Mono coils. Due to narrower detection zone speed of sweep whould be slower. Sweeping too fast may miss small gold because the signal may be filtered out.
Metal Detector Coils Get Them Right For The Ground Conditions
Double D Coils