The Teleporter disc is a key item found in the level Escape with the Iris in Tomb Raider Chronicles. Finding it isn't simple since it's located in a room with seven suitcases. If Lara opens a wrong case, she'll explode as she sets off a bomb. The right suitcase is the lone one in the third row. This can be figured out by activating an X-ray machine.
The Teleporter disc is used alongside with the Iris artifact to teleport Lara to another room.