Give your bass a new voice with a custom Bartolini on-board preamp. These harnesses are prewired for easy installation and offer a variety of configurations to meet your needs. Bartolini is one of the most respected & trusted pickups & electronics builders in the industry and offers some of the finest electronics using only the highest-grade materials. Every Bartolini preamp & pickup is hand-built right here in the USA. All preamps feature a Gain trim pot on the module for fine-tuning, and all tone & blend pots feature smooth action & center indents with 6mm knurled split shafts. Controls knobs with set screws are recommended, but not included. Controls are: -Volume with Push/Pull switch for Active/Passive modes -Pickup Blend -Bass Boost/Cut -Mid Boost/Cut -Treble Boost/Cut -3-Way toggle switch for Mid-frequency selection (switch between 250 Hz, 500 Hz, and 800 Hz) What's in the box: (1) Pre-wired Preamp Harness (1) Extra Battery Connector for 18 Volt installations (requires soldering if used) (1) Wiring Diagram PLEASE NOTE: Preamps that have been installed or attempted to be installed are not returnable unless defective. Check to make sure you have the correct control configuration & check the fitment before attempting to install it.