The Amulet-key held in Osiris' hand.
The Amulet-key was a small device used by the former Goa'uld System Lord Osiris to open a concealed apartment in his temple on Earth. The device also operated other controls in his temple, which hid many pieces of Goa'uld technology including a Kara kesh, Transportation rings, and a personal cruiser which belonged to Osiris and his queen Isis. (SG1: "The DVD Collection 2")
When Osiris was freed from his canopic jar and took over the body of Sarah Gardner, he used this device to open the concealed apartment in his temple, taking the Kara kesh and escaping into his ship. (SG1: "The Curse")