The Humminbird Fish Finder 688ci HD XD Combo is a unit that combines chartplotting functions with extreme depth fish finding capabilities. The head unit of this Humminbird is pretty much similar to the other units of the 600 series. It has a 5-inch diagonal screen, brilliant color and backlit, 480H x 640V pixel resolution. Has a power output of 1,000 Watts (RMS) / 8,000 Watts (PTP), being capable of scanning depths up to 3,000 feet.
It has Dual Beam Plus Sonar, and Xtreme Depth (that?s what