Review Garmin GPSMAP 421 4-Inch Waterproof Marine GPS and Chartplotter

The GPSMAP 421 is a compact chartplotter that features an ultra-bright 4 in (10.16 cm) QVGA color display along with an improved high-speed digital design for increased map drawing and panning speeds. It’s ready to go with a built-in, satellite-enhanced worldwide basemap and an easy-to-use ...