To provide a spark plug with improved heat resistance and an internal combustion engine in which that spark plug is mounted where there is good conduction of the heat near the opening on the combustion chamber side of the mounting hole for the spark plug provided in the engine and the effects of thermal stress occurring near that opening are mitigated. Two panels can be held together along respective internal edges using Velcro\u2122, with the panels cooperating structurally to provide their own support. A unitary flexible circuit electrically connects the subassemblies and is physically integrated between two inner layers of each subassembly’s discrete, rigid, multilayer printed-circuit-board. The top edge of the skirt is folded around a draw string and has opening at the ends exposing draw string pulls.