Okay, I went and did a little research and found the information below at Unofficial Humminbird Side Image Forums www.sideimageforums.com - Index page published by Wayne P. » Sun Jan 31, 2016:

(ALL Side Imaging units except the ONIX and ION use the exact same transducer and they do not have a dedicated DI crystal. The DI view is software blending of the two SI pulses. The ONIX SI unit's transducer has a dedicated Down Imaging crystal like a Down Imaging transducer has. BUT anything displayed in the DI view is "somewhere down there" so you won't know what direction. ONLY SI or 360 can show you where.)