Bartolini HR-5.4AP/918 Preamp Harness - 3-Band EQ w/ 5 Control Knobs & 3-Way Toggle Switch - Active/Passive Switchable - Pre-wired for a Two-Pickup Installation 3-Band EQ w/ 5 Control Knobs & 3-Way Mid Frequency Selection Toggle Switch Active/Passive Switchable Can be wired for 9 or 18 volt configuration Prewired for easy installation Fits most basses with 5 holes for control knobs and 1 switch hole