The Lowrance Mark-4 is the newest and greatest value in advanced performance, affordable marine electronics. The Mark-4 features easy-to-use menus and fast installation. The high-bright, sunlight-viewable, grayscale display is packed with all the features you could want. The Mark-4 includes impressive detail on the 3.5 in/8.9 cm screen that virtually expands to 4X its size with the integrated TrackBack feature. TrackBack gives you greater control of your time on the water. Simply move the cursor back through sonar-display history, quickly identify baitfish, game-fish or structure and save a waypoint. Includes a low-profile, high-speed, transom-mount, 83/200 kHz Skimmer transducer with built-in temp sensor, and trolling motor-mount bracket option.The Mark-4 is easy-to-install with a quick-release mounting system featuring a tilt and swivel bracket for plug-and-play use. Or it can be flush-mounted using the accessory mounting-kit option. For fast and smooth one-hand operation, the Mark-4 design includes easy-to-use page and menu controls. The simplified menus makes it easy to learn and use right out of the box. Comes preloaded with a detailed basemap, and is compatible with Fishing Hotspots Pro, Navionics Gold and Premium charting upgrades through the built-in, waterproof microSD card slot.