A force-dome was a localized form of defensive shielding, created during the last decades of the Galactic Republic as a security system for remote outposts. The force-dome used a collection of crystals, similar to those used in the construction of a lightsaber, to generate a hemisphere of protective energy. Its size could be modulated by the amount of power and the number of crystals used, but was usually limited to a few square miles in surface area. The shield produced by the force-dome was capable of repelling even the heaviest of projectile weapons, but could eventually be pierced by ion-type weapons.