The Mk.III with lasers. Nuff said. The Mk.IV add pinpoint precision to the arsenal of the AIN pilots. The combination of 3 weapons systems multipled by 4 due to the Copperheads squad patterns leads to devestatingly effective small strike craft. The Mk.IV is crewed by veteran squads who have survived the battlefield with their admittedly short lifespans as Copperhead pilots.