K&K Trinity Pro Classic System, the Trinity Pro System is a dual source pickup/microphone system with an external dual-channel pro preamp for guitars and similar string instruments. It features the new & updated Trinity Pro Preamp, which adds a phase switch to the microphone channel for improved feedback resistance and a smoother overall tone. It consists of: Pure Classic Pickup, the Trinity Microphone with integrated 5" gooseneck and 20-20.000 Hz frequency range, the Trinity Pro Preamp, 2-channel external preamp with adjustable gain-volume-bass-mid-treb for each channel & phase switch for the microphone channel, stereo endpin jack and a 6-foot stereo cable.