I have a NASA Tom certified CZ3D and a CZ5. Both are in excellent condition. The CZ5 is a little deeper, but it only has 3 audio tones whereas the CZ3D has 4 audio tones. The CZ5 does better at parks with modern trash, but the CZ3D does a better job of finding older deeper nickels. Both are GREAT at finding deep silver coins and handling EMI. I DON'T need both! Decisions, Decisions, Decisions.