Garmin GPSMAP 498 Sounder 5-Inch Waterproof Marine GPS and Chartplotter with Sounder (External Antenna) Product Type - GPS - CCFL backlight for display and keypad - Ultra-dim backlight for nighttime operation with user programmable levels for day and night - Unit dimensions - 6.3-inch H x 6.3-inch W x 3.3-inch D (external antenna), 7.1-inch H x 6.3-inch W x 3.1-inch D (internal antenna) - Power output - 500 watts (RMS) 4000 watts (peak to peak), dual frequency 400 watts (RMS) 3200 watts (peak to peak), dual beam Depth 1,500 feet (dual frequency), 900 feet (dual beam)