Spruance Leader: Submarines ExpansionExpansion

From BoardGameGeek:

The SSN Expansion adds SSNs for use instead of Task Force ships. Your SSN acts alone to clear out Soviet forces, adjusting your SSN depth to attack ships and subs above and below the Thermal layer. This expansion includes: 8 SSNs (48 cards) 4 SSN Commanders (24 cards) 1 Counter Sheet 4 Campaigns SSN Expansion Rulebook Summary Sheet