Humminbird 688ci HD DI Combo features a High Definition 480H x 640V 5", 256 color display with backlight, DualBeam PLUS sonar and Down Imaging sonar with 4000 Watts PTP power output, GPS Chartplotting. In addition, it includes a card slot for maps and saving waypoints, as well as three programmable preset buttons to save your favorite views. Maximize your angling experience with the Humminbird 688ci HD DI Combo fishfinder GPS system. Internal GPS Combo with Down Imaging. 409460-1 The 600 Series when screen size isn"t everything but advanced features are a must, the smart money is on the 600 Series. With an unbelievably clear, HD display, this incredible value delivers more options than you can shake a rod and reel at. Choose from Imaging Sonar, SwitchFire Sonar and GPS cartography. Get it on the water, and this bad boy is touch to beat. Because you don"t need to be a big fish, to put up a big fight.