GPSMAP 421 Chartplotter

Features an ultra-bright 4" QVGA display along with an improved high-speed digital design for faster map drawing and panning speeds. Plus, these waterproof units have a high-sensitivity internal GPS receiver, so mariners will always know their position at sea. They are ready to go with a built-in, satellite-enhanced worldwide basemap and Garmin's proven easy-t0-use interface designed to help you navigate the open waters with ease. Both models are compatible with various NMEA 2000 components, inculuding Garmin's full lineup of NMEA 2000 marine sensors and autopilots. 
Features and Specifications:

• Ultra-bright 4" diagonal QVGA display, 240 x 320 pixels - over 800 nits of brightness
• NMEA 2000 certified for seamless integration with the Garmin marine lineup
• Preloaded worldwide marine basemap
• Compatible with GXM 51 for XM Satellite Radio and XM WX Satellite Weather
• High-speed processor for fast screen redraws and smooth panning
• Streamlined user interface makes it simple to select modes and features
• Single SD memory card slot for BlueChart g2 Vision cards, as well as saving waypoints, routes and tracks to a SD card
• Optional BlueChart g2 Vision cards provide marine chart detail and enhanced navigation features like Auto Guidance, satellite imagery, 3-D Mariner's Eye View and 3-D Fish Eye View
• Backlit keypad for easy operation in low light conditions
• Unit dimensions: 5.0"H x 5.7"W x 2.7"D (12.7cm H x 14.5cm W x 6.9cm D)
• Owners Manual :  Download