What is the difference between Concentric coils and DD coils?

Question: What is the difference between Concentric coils and DD coils?

Answer: The Concentric puts out a snow cone-shaped field (shaped like a snow cone), the DD field is more like the "knife blade" of the Concentric (shaped like an I). The DD coil separates much better and gets more even depth especially in mineralized ground.

Relevant to: Coils