An object is to provide a vent filter in which a vent film is less likely to be broken when cut and a measure to shrinkage is taken while the characteristics and functions both inherent to the vent film are being kept. The advantage of the first protection device is that it eliminates the need for a band-pass filter in the front end module, when used in a mobile telephone. The method and system also include learning whether performance of the automatic transmission can be improved utilizing the positioning data and the transmission data. The rear wall has an opening formed therein to effectuate engagement with the wall outlet.