A spirit shield generator is a harness of ARB material and Velcro, which can be worn over clothing or armor. It stretches across the torso. When plugged into an A/O port, it activates a number of spirits trapped in the ARB. These invisibly circle your body, on the alert for incoming ranged attacks. When you are the subject of such an attack, you may make an Powers check with no shot cost. The difficulty is the damage value of the attack that has just been made against you, after modification for the Outcome of the attack roll. If you make it, a tiny, grotesque spirit partially materializes and devours the projectile or thrown object: you are not hit and take no damage. The spirit, on the other hand, is then released from it's bondage and abruptly vanishes.
Spirit shield generators provide no protection against hand-to-hand attacks, but does protect against physical Blasts.
When your character first gets a spirit shield generator as a schtick, it has eight captive spirits. This is the generator's maximum capacity. To replace a spirit, you must spend four hours exclusively engaged in a ritual: then you make an Powers check with a Difficulty of 7. If you succeed, you have replaced the spirit. If you fail, you have wasted four hours. Since characters should never be wasting time while on-stage, expect your GM to make this as inconvenient as possible. You usually have time to refill the device between scenarios (no roll required).