The present invention is applied to the case that in a communication system establishing the communication between a radio intelligent terminal and a server via gateway, it is necessary to exchange from a gateway to be used originally to other gateway because of any reason. The base portion is generally made from two flat panels substantially free of overlapping portions and the skirt portion has a plurality of overlapping portions which allow the skirt portion to expand outwardly from the upper end of the base portion. One or more of the control signals can be bypassed to investigate the effect of each of the control signals alone, or in various combinations. The side walls and the base wall comprise a non-metallic material. The straight stream nozzle may be adapted to direct a stream of fluid to a removal mechanism.