Humminbird 161 Combo 4-Inch Waterproof Marine GPS and Chartplotter Full-featured fish finder and 16-channel WAAS GPS receiver with chartplotting and sonar all in one 20-degree, 200 kHz single-beam sonar optimized for coverage and precision bottom detail Built-in 4 nautical mile resolution UniMap of USA inland lakes, rivers and coastal areas 4-inch FTSN LCD screen with 320 x 240 lines of resolution in 16-level grayscale Reliable to 600 feet of depth, waterproof construction, and 1-year warranty