Originally, the mini humbuckers were only found on the Gibson Les Paul Deluxe. The narrower magnetic field produces a clear and compact sound compared to normal humbuckers. In the 1970s, these pickups were often replaced by stronger (and often significantly lower) pickups - today, where gain and sustain are no longer a big issue thanks to the modern amps and pedals, you can appreciate the great sound of these pickups.
The model for the neck position has a little less output and sounds wonderfully bell-like - ideal for the big band of guitarists, where a normal humbucker at the neck always sounds messy.