A portable shower head with an air inlet cover includes a decorative cover, a middle cover with soft rubber nozzles and a shower head body. The mini-charts may be advantageously used to show criticality of impact to assist a user with incident avoidance andor to provide fast incident resolution. A non-contacting range sensor, coupled to the shaft, generates a pulse-width modulated signal in response to rotation of the shaft. A pinion freely slides on the clamp shaft within the housing and converts rotational movement from the clamp shaft into linear movement via a meshing rack gear. In particular, the invention provides high optical quality molds and inserts useful for manufacturing silicone hydrogel contact lenses. The client presents the short-term certificate to the application program for authorization and demonstrates that the user has knowledge of a private key corresponding to the public key in the short-term certificate.