The present invention provides an expandable fusion device capable of being installed inside an intervertebral disc space to maintain normal disc spacing and restore spinal stability, thereby facilitating an intervertebral fusion. The vertical heterojunction bipolar transistor includes a barrier layer between the intrinsic base and the extrinsic base that blocks or reduces diffusion of a dopant from the extrinsic base to the intrinsic base. Additionally, the bus frequency is set according to the length of the bus between the devices that are a part of the transaction and, correspondingly, the expected amount of impedance there between. The pusher extends from the connector body and surrounds the receiving hole. The broadcast sent to the user can be either a radio program instantly being broadcast by the identified station at the time of the call or a recording of a broadcast carried earlier. The apparatus includes at least one bypass line adapted to guide a refrigerant to bypass a main line through which the refrigerant flows between an outdoor unit and an indoor unit, a strainer arranged at the bypass line, a first valve arranged at the main line between opposite ends of the bypass line connected to the main line, and second valves arranged at the bypass line.