A cap for an aerosol can is provided comprising a recessed portion configured to retain a sprayer for the can wherein the sprayer is contained in the recessed portion when stored in the cap. An opposed second surface 44 of the member 40 is in contact with a fluid 25 to be monitored. The present invention also discloses a packet transmission device and a packet transmission system which can realize high-capacity communication over an SDH transmission link by mapping the packets directly into an SDH section payload without adding any VC path overhead in order to use the entire SDH section payload area. By alternating stimulation and recording at gradually increasing levels, one can determine the minimum input that creates a neural response, thereby identifying the threshold stimulation level. The method comprises administering a tetracycline compound in an amount that is effective to treat shingles, but has substantially no antibacterial activity.