Custom designed and built in house.
These bobbins are designed to give you the ability to get true P90 tone out of a humbucker sized pickup by being taller than the normal alternatives used.
Many humbucker sized P90 are made with either humbucker bobbins or P90 bobbins chopped down to fit under a humbucker cover. Both of these happen to have exactly the same winding area, so the myth that a P90 bobbin chopped down provides a more accurate P90 tone is false.
A P90 is much wider than a humbucker to accommodate all the winds - meaning that you just can't just chop down the bobbin to humbucker size. We need to create more room on the bobbin to get these additional winds, but you can't extend it outwards or it won't fit in a humbucker space. We extend it downwards instead!
Coming in at 14mm tall (with 10mm of winding depth, as opposed to a humbucker/P90's usual 6mm) These bobbins add the additional winding area required for proper P90 winds.