Garmin STRIKER 4 3.5" Fishfinder | CHIRP Sonar | GPSEntry level 3. 5" CHIRP sonar + GPS fishfinder. Button controls, no touchscreen, no mapping, just simple, reliable fish finding at the lowest Garmin price tier. Garmin STRIKER 4 The Garmin STRIKER 4 is the entry level Garmin fishfinder, the starting point of the lineup at $159. It's a 3. 5" color fishfinder with CHIRP traditional sonar and built in GPS for waypoint marking. Not a touchscreen, this uses buttons. Not a chartplotter, there are no maps.