HB models with "DI" in the model name are dedicated DI units - always have been...(Altho older numbered series and HELIX series with "DI" in the model name had no SI) ...

HB MEGA SI series have dedicated DI and SI in the same xducer ...
ONIX and SOLIX SI series also have dedicated DI/SI in the same xducer ...
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All Lowrance series with DI have always been dedicated DI ...Navico owns the DownScan patent - any other brand with dedicated DI pays Navico a license fee to use the DI technology...
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All Garmin series with DI (except the new bundled ClearVu) have dedicated DI ...

(Note...: The Garmin court litigation only affected future units bundled with a DI xducer - Garmin refused to license the DI technology from Navico and decided instead to offer the ClearVu xducer in their bundled units - only the ClearVu xducer has computer DI from SI ... All GT xducers, past and present, have dedicated DI ... The GT xducer can even be connected to the Garmin unit that came bundled with the ClearVu xducer and still get dedicated DI from the GT xducer) ...

Rickie