Anti-Strike Craft Frigates, often simply called Flak Frigates, are used to counter enemy Fighter and Bomber squadrons, and to counter enemy Long Range Frigates. Although they do not excel at other types of combat, they are capable of enduring large amounts of damage from other frigates.
- Armor: Heavy (25% damage from Anti-Strike Craft Frigates, Fighters, Colonization Frigates, and Scout Frigates; 75% damage from Assault Frigates; 125% damage from Light Frigates, Support Cruisers, and Siege Vessels; 50% damage from Bombers; 125% damage from Heavy Combat Cruisers; and full damage from capital ships)
- Damage: Anti-Very Light (125% damage to Fighters; 50% damage to Heavy Combat Cruisers; 25% damage to capital ships; and full damage to everything else)
- Main article: Garda Flak Frigate
- Main article: Defense Vessel
- Main article: Junsurak Sentinel