From Bartolini:
A Pre-Wired harness saves the time and aggravation of wiring your pre-amp and pots into your instrument. They feature our industry leading pre-amps and premium audio-quality potentiometers with smooth control and ready for years of rugged use.
The HR-4.7AP/918 uses a 3-band EQ and pre-amp.
Two holes for Volume control: Volume (with Active/Passive push-pull switch) – Blend.
Three holes for Tone control: Treble/Bass Stack -Mid (+ 3 freq toggle switch).) – Bass.