The purpose of this RFI is to identify sources capable of providing a Hardware Content Filtering Diode (HCFD) solution to support the secure transfer of All-purpose Structured EUROCONTROL Surveillance... The purpose of this RFI is to identify sources capable of providing a Hardware Content Filtering Diode (HCFD) solution to support the secure transfer of All-purpose Structured EUROCONTROL Surveillance Information Exchange (ASTERIX) data from an unclassifed network to a SECRET network for the Common Aviation Command and Control System (CAC2S).