The ULTIMATE Probe may not be produced any more....
The OTT Technologies Periscope.
This is a 15" Hardened Probe that uses Conductivity and Ferris Content much like Minelab does in their FBS Explorer II.
You push the probe into the soil and as it approaches the target, the pulse rate increases. When contact is made with the metal.... FLATLINES, much like my V-1 does when a CHP Cruiser running Dual Directional Golden Hawk Radar Guns passes in close proximity.
The Periscope has a Verify Switch A/B.... which then determines whether the metal is Ferrous or Non-Ferrous. It can even tell the difference between aluminum Tabs and Gold Rings by the audio responses.
Bad News: $550.00 and although Ott industries is no longer producing them, still supporting those models out there as far as service. The Periscope also used Four C Cells in a pack you wore on your hip. Two of the Four were used as Back Up. Worked great at Tom C's MT-Big Rec and I cleaned house on Manny's Explorer II thanks to this surgical pin point process.
Putting the Periscope aide, the Sun Ray Probes are superior in terms of depth and NO cross talk with your detector's circuit.
Self Contained Units: Treasuremate or Uni-Probe. Uni-Probe makes a cleaver high quality Headphones with the electronics built in and probe attached.
Those 'CHEAP' ones are exactly that, and considering one customer I know who complained about sending it BACK THREE #$!$#!@$ Times.... suddenly, NO Bargain, in spite of its initiall Bundling Discount.