GARMIN GPSMAP 520 PRELOADED W/ WORLDWIDE SATELLITE IMAGERY For mariners with a keen eye for value, the Garmin GPSMAP 520 versatile chartplotter delivers a lot of navigation for the money. The Garmin GPSMAP 520 features a bright 5? QVGA color display, satellite-enhanced worldwide basemap imagery, and an SD card slot that makes it easy to add features with the optional BlueChart g2 Vision card. Like all Garmin plotters, the Garmin GPSMAP 520 utilizes WAAS/EGNOS-enabled GPS receivers for extreme high accuracy (typically within 3 meters).