This is dual wing pickup. There are two piezo elements on the top and bottom of the casing in each pickup. The addition of the pickup on the treble side of the bridge makes for brighter notes from the D & G strings.  Female 1/4" Jack included 

Installation:
The standard bridge wing will need to be opened up with a wood file to fit this pickup. The pickup should fit snug, but not too tight. If it's too tight it will cut off the low end sound of the pickup. If it's too loose it will cause feedback. You can use wood shims or guitar picks to place in the wing if you make the gap too large. Velco strips are included to fix the jack to the tailpiece or on the strings between the bridge and tailpiece.