Droideka personal shields
Nature of the Shield
The Droideka is a dangerous combat droid not only because it sports dual repeating blasters, but also because it carries a personal shield. This shield activates when the Droideka opens two panels at the base of its "hip." The shield can deflect incoming blaster bolts, leaving the Droideka to concentrate on firing its weaponry at the enemy, rather than seeking cover.
It should be noted that only the Droidekas stationed on the Trade Federation ships and in the palace on Naboo showed personal shields, while the Droidekas employed at the Battle of Geonosis did not. This suggests that not all models of Droideka are equipped with shield systems.
Droideka personal shields can easily withstand fire from several blaster small arms for an indefinite period of time, but even one shot from a starfighter's blaster cannons can penetrate the shield and destroy the droid. Droideka shields are permeable to slow-moving objects, and Republic troops developed a technique for throwing EMP grenades ("droid poppers") at them with just the right speed for the grenades to roll through the shield before detonating.