Bacta Tanks is a technology that can be researched at the Command Center in Tech Level 4. It costs 200 Food and 300 Nova, and lets garrisoned units heal 4 times faster. It is available to all civilizations except the Trade Federation and Wookiees.
This technology is useful for players that use garrisons to heal units, rather than Medics and Workers. It is particularly apt for civilizations with lots of mechanical units, who'll otherwise have to spend resources to repair their units.
"Units garrisoned within buildings and Turrets heal at four times the normal garrison heal rate."