Bartolini 9J1 pickups are a split coil hum-cancelling design. Think of them as a “P-Bass* pair in box”.
The Bartolini 9J1 set has bright Neck tone and deep Bridge tone. The windings on the 9J1 set yield much more “growl” from the Bridge pickup. They are very similar to the old Bartolini 94J pickups, just slighlty brighter at the bridge.