The present invention provides a communication system for transmitting messages from one or more dispatcher stations to and from one or more stand-alone, two-way pagers via a radio frequency communication channel, namely, the short message service of the Global System for Mobile Communications cellular telephone network. A veil cloth is applied to the outer surface of the rim portion and impregnated with resin material to complete the impeller structure. The actuator can be actuated by a pressure medium to fix the gearwheel to the shaft. The first panel may also extend beyond the second panel such that both panels may collectively form a wall.