PS: check out this site if you think all OKM stuff is crap:
http://kts-electronic.com/index.php?lang=en
KTS Electronic also built deep search devices - I visited Mr. Yazdani 15 years ago personally and bought a used Fisher 1266-X from him which still works!
I can assure you that he self developes / sells real working hitec detectors and that he's a very skilled and kind engineer!
Look here if you want a very good PI detector with discrimination and 4 different coils for 1999,-Euro:
http://kts-electronic.com/content/view/29/79/lang,en/