The transporter chamber was Gary Seven's means of transportation around the planet Earth and back to his home planet more than 1,000 light years from Earth. The way the chamber worked is unknown, but when in operation, the chamber produced a cloud of a blue fog-like substance that enveloped the chamber. The chamber was controlled by the Beta 5 computer and was the first known transporter to be in use on Earth, especially given the time period of 1968 and its use for an unknown number of years before.
The transporter beam could be intercepted by another transporter unit. This occurred when Gary Seven was in transit to Earth and his beam was accidentally intercepted by the USS Enterprise commanded by James T. Kirk. This would seem to dictate that both transporter technologies work on similar principals, but there is no further information on this device. What is known is that Gary Seven's transportation chamber is more powerful than that of the Enterprise, for it was able to re-direct the transporter beam of the Enterprise back to it, and instead of Gary Seven re-materializing in the transporter room of the Enterprise, he re-materialized in the transporter chamber.
When not in use, the chamber door, which resembled that of a safe when it was closed, was hidden behind a shelf holding Martini glasses. The shelf and the brown wood finish surrounding it split down the middle and slid into the adjacent walls, allowing the chamber door to open. This action was achieved by moving the right pen on Gary Seven's desk downward. (TOS: "Assignment: Earth")