Symbios “Blue” is identical to the Symbios "Silver" version with the single exception that it does not include handset integration for Halcyon rebreathers. It does include a fixed PO2 setpoint mode for non-integrated rebreather diving. The Blue version offers compatibility with the wider Symbios wireless ecosystem, including the Symbios Tank Pod (aka AI tank-pressure transmitter), DPV interface, and GPS Pod. Unless you foresee diving with a Halcyon brand rebreather, the Blue version represents a better value.