A Goa'uld cloaking device was a device used by the Goa'uld to become invisible to human perception. Hathor had a cloaking device prior to escaping the SGC. She also had it on Eskal. Nirrti experimented with phase shifting technology in an attempt to better fight the Reetou, but the SGC recovered her device when she followed SG-1 through the Stargate. Anubis later gave one of his Ashraks a cloaking device, and used it to go on a killing spree at the Alpha Site. (SG1: "Fair Game", "Rite of Passage", "Allegiance")