Besides the standard Bubble Shield that deploys a ten second dome shield as protection against enemy fire, the following armor is also available. Each of them have various recharge times.

Overshield (500 credits)
Instant shield recharge and invincible for 8 seconds.

Seeker Drone (750 credits)
Explosive homing drone that remains active for 10 seconds.

Airstrike (1,000 credits)
Several explosives that last for 2.5 seconds.