Incomparable compared to the usual piezo, the cell is very well fitted and the preamp / buffer avoids that any contact microphone is: take your spectrum in two, leaving only a small its garish .dropoff window
Here impedance matching avoids low cut.

The box runs either on batteries or on 48v is handy.

The size and shape of the cell may sometimes be problematic in certain applications.
Ideal with contact microphones it is in have several different sizes and with different fixing systems. The Barcus Berry, as soon as the surface on which it is placed is not flat, sturdy it's hard to get a broadband response.

The set is solid, very fine cable (to avoid influence cell behavior) is handled with care anyway.
The adhesive sold is very efficient, and more transparent than the patafix.

I personally serve as sources of musical extras (field recording, sound design).