HUMMINBIRD Apex 13 Mega SI plus The APEX 13 MSI+ CHARTPLOTTER provides the clearest sonar imaging on the sharpest multi-function display that that anglers have ever seen. Industry-leading MEGA Imaging+ and Dual Spectrum CHIRP sonar come standard, with even more performance from a dedicated sonar channel for accessory 2D CHIRP transducers up to 2kW.