Increases your Energy Shield's Durability and Recharge Rate by a given percentage.
At higher rarities, some Shield Boosters have the added effect of refilling 35% of your shield HP whenever your shields are depleted, with a cooldown of 5 minutes.
This upgrade stacks with itself and with Energy To Shield Converter additively (if you have 1000 shields and you install 2 upgrades, +100% each, you'll have 3000, not 4000 shields).
