Hello, Timbertodd,

SMART PRO and Vista X are different units, they work on similar frequency, but the coils are not interchangeable, yes. If you connect SMART PRO coil to Vista X or visa versa the units will work somehow, but not at full capacity. SMART PRO is the third unit from this series. Before it was SMART and SMART PLUS what we made many years and continue make. So, SMART PRO is made on the basis on SMART PLUS, but their coils are not interchangeable too.
As circuit design and method of operation Vista X and SMART PRO are different.
In fact, of all our devices, only the coils are interchangeable for:
- Vista WARRIOR and Vista MINI MAX;
- Vista SMART and SMART PLUS.