In general, one embodiment of the invention is a air monitor adapted to a wireless network. The elastic cord draws the percussion woodblock and the vibration absorbing material together into a flexibly fixed position so that the instrument is playable. Using these predefined access keys, an author andor portal designer maps the predefined access keys to browser key equivalents, thus providing consistent navigation across an application or portal. The crossover time determines the width of an output signal and is directly proportional to the voltage level. Typically, the one or more packing layers are within the annular zone. The Bkoff should be large enough to enable the traffic that needs to be accommodated by the channel.