Tollan phase device
From The Stargate Omnipedia
Device capable of allowing any object armed with the instrument access through any wall or barrier, including the Stargate Iris on Earth. The devices are worn about the arm, and can be shared by more than one individual if they are in direct physical contact.
KEY EPISODES
Enigma - Confined Tollan refugees use their phase devices to move freely in, out and through Cheyenne Mountain.
Pretense - Narim uses his phase device and sends Shroedinger the cat through the iris first to Earth to notify the S.G.C. a friend is coming, then comes through himself.
Between Two Fires - The phase device is instrumental in allowing Narim and SG-1 free access through many parts of Tollana structures in order to prevent the fall of Earth to the Goa'uld.