In an embodiment, the size of a filter in a search engine is dynamically adjusted in order to reduce filter error. The level shifting circuits receive a variable and fixed input and generate a variable and fixed output that are level shifted with respect to the input signals. The power-on-reset signal generating circuit is coupled to the bias circuit, and is for generating a duplicated voltage by duplicating the output bias voltage, wherein the power-on-reset signal is generated according to the duplicated voltage. A means to assist in the removal of the battery is provided, as is a spring loaded battery carrying strap. Methods of sterilization include gamma irradiation.