The GPS tracker is a standard device implanted into all bionic patients treated by The Berkut Group. In Sarah Corvus and Jaime Sommers it is alternately known as the ocular tracking device, because it is a part of the bridge between the bionic eye and the brain. In both these patients, it is located at the base of the cerebral cortex. It is integrated with the streaming optical interface, such that their use is indivisible. It can be turned off by the patient by intense concentration. In Jaime, turning the device on or off is currently a difficult process which results in nosebleed. ("Sisterhood")