From the manufacturer:
The LR Baggs Anthem Acoustic Soundhole Michrophone/Undersaddle Guitar Pickup has all of the essential tools in one complete system. The feather-weight preamp and controls include: volume, mix, phase and a battery check. The mix control blends from the augmented TRU•MIC position to Element pickup only.

• The patented TRU•MIC carries the majority of the guitars’ frequency range while the Element Pickup carries the lowest frequencies
• Mix control blends between the TRU•MIC augmented with low frequency support from the Element Pickup and full-range Element Pickup
• The mic is highly feedback-resistant
• Noise cancelling microphone technology eliminates any annoying honky or boxy qualities from the inside of the guitar
• Mic installs easily on the bridge plate with peel and stick adhesive
• Mic and pickup levels preset for optimum performance
• Soundhole preamp includes volume, mix, phase inversion, battery check, and mic trim controls
• All discrete pre-contoured soundhole preamp with preset crossover
• Element Pickup fits most common string spacings and saddle width
• Comes with battery bag for secure and unobtrusive battery retention

This item has a special packaging from the manufacturer.  If the manufacturer's seal is broken or internal packaging is not "as new" the item cannot be returned.