Rotary switch lighting device

A watertight electrical device comprising:

• a battery having a voltage;
• an electrical element in electrical connection to said battery;
• a power control for applying the voltage to said electrical element;
• a case in which said battery and said electrical element are disposed, said case at least partially supporting said power control;
• said power control including an activator comprising a shaft, said activator rotatably connected to said case through a hole in said case;
• a sealing means disposed in an opening between said activator and said case, the sealing means physically contacting the shaft;
• upon an external case pressure exceeding an internal case pressure, said sealing means being at a first disposition relative to said opening and withstanding a first pressure differential between said interior case pressure and said exterior case pressure;
• and
• upon the internal case pressure exceeding the external case pressure, said sealing means being at a second disposition relative to said opening and withstanding a second pressure differential between the internal case pressure and the external case pressure, said second pressure differential being less than said first pressure differential, wherein, in said first disposition, said sealing means prevents ingress of water into the case and in said second disposition, said sealing means allows the escape of gas from within said case.