Abstract: A primary battery includes a positive electrode, a negative electrode, and an electrolytic solution. The positive electrode includes manganese dioxide. The negative electrode includes a lithium-based material. The electrolytic solution includes an alkali metal compound represented by Formula (1) and a dicarboxylic anhydride compound represented by Formula (2). MeN(CxF2x+1SO2)(CyF2y+1SO2)??(1) where: Me is an alkali metal element; and x and y are each an integer of 0 or greater. W(—C(?O)—O—C(?O)—)z??(2) where: W is a benzene-based aromatic ring from which 2z-number of hydrogen atoms are eliminated; and z is an integer of 2 or greater.

Abstract: A restriction indicator having a contactless switch device for indicating a restriction in filter elements of fluid filters having an intake side and a negative pressure side. The restriction indicator includes a photointerrupter having a light emitting device and a light receiving device. The light receiving device provides an electrical signal indicative of increased negative pressure in the negative pressure side.