Sequential circuits samplers

Another question regarding filter:
Does anyone know what the small pcb is that hovering over the filter chips?  It is connection to one of the pins of each of the chips (pin 8 or 15 depending on how you look at it).  I was wondering if swapping filters might somehow not work if each filter had to be in a specific place relative to it's wiring placement on the hovering pcb (this doesn't seem totally logical, but then again, I've never seen filters attached like that.)