K&K UltraPure Mini for Steel String GuitarsThe UltraPure System is an active system for acoustic guitar. It consists of our award-winning Pure Pickup, an onboard preamp with soundhole access, an endpin jack, and a Velcro mounted 9-volt battery holder.The UltraPure Preamp features /-20 db bass/low, K&K's proprietary wide band midrange, and treble/high controls, plus internal gain trimmer. The addition of a phase switch is one of the most important tools for live sound amplification. Also includes a volume control and low battery indicator. All features are easily accessed at the soundhole.Features:-• Volume control slider• Proprietary K&K 3-band EQ with /-20dB Bass, Mid and Treble controls• K&K’s extra wide band midrange filter, especially geared towards acoustic guitar• Phase switch: flips the phase 180 degrees if pressed in• Low battery indication light: comes on at about 6.5-volt operating voltage. There will be at least 3-4 hours playing time left.• Adjustable input gain: a small blue trim pot on the bottom of the preamp