Stated in Features for the G3:
Industry-leading Humminbird sonar: Equipped with MEGA Side Imaging+, MEGA Down Imaging+ and Dual Spectrum CHIRP sonar to keep you on the fish. MEGA Imaging+ provides views up to 250' under and out to either side of your boat and Dual Spectrum CHIRP shows exceptional 2D sonar with superior target separation and fish clarity.
This is stated for the G2:
NEW MEGA Side Imaging+: See the world below like never before with crystal-clear viewing out to 200 feet on either side of your boat. You'll unlock more fish and structure with 20% more detail than MEGA Side Imaging Sonar.