I got my set back in 2005 and wrote them up here ->
https://www.talkbass.com/threads/q-tuners-are-good-for-nothing.166151/
They are the brainchild of Erno, a gentleman in the Netherlands who suffers Asperger's, which makes him a bit of a propeller-head for this type of thing. I've not been in contact with him for a number of years but recall he was ill and may have now passed. I helped them with their marketing, particularly helping them write copy that most normal people could understand; their materials were very technical and English wasn't their main language. IIRC there may have been some legal issues with people ripping off their tech that was causing problems as they got more successful.
Unlike other pickup designs that use a wide magnetic field and almost brute-force to create an electrical signal, Q-Tuners use a definable part of the frequency spectrum -
the Q in a parametric EQ - that you "tune" with the screws appearing as pole-pieces around the windings. The windings are computer controlled to be perfectly matched between sides, making them the quietest pickups made and the greatest bass tone you'll ever hear.