Recently XP announced that the existing stock coils will be superseded by the new X35 coils.
Why have they done this you may ask?
Ever changing technology
A spokesman for XP told me, as technology moves on so does XP metal detectors, although they are a relatively small company they are constantly investing in new technology and the way products are made.
Coil construction has moved on very fast, XP have recently invested a lot of money in state of the art robots that can quickly build coils to a constant high standard every time, and are much more precise than a person.
The X35 coil offers better stability and has the added advantage of a wider frequency choice, plus a boost mode if using V5x software.