Shield Modifications is a technology that can be researched at the Airbase in Tech Level 4. It costs 250 Food and 500 Nova, and gives self-shielding to Fighters and Bombers, as well as unique units like the Airspeeder, A-wing, and Jedi Starfighter. It is available to the Rebel Alliance, Republic, Royal Naboo, and Wookiees.
This technology keeps the player's aircraft alive far longer. Not only does it effectively double their Hit Points, but the shielding also regenerates. Since most aircraft have low Hit Points, the shields will regenerate fully in a matter of seconds, meaning that they won't have to stay out of combat long to return to full form.
"This significant Tech Level 4 technology bestows all Aircraft with regenerating personal shields, effectively doubling the amount of damage they can withstand."