The present invention provides a unit sheath adaptable to a glow plug or a thermocouple, which is improved in durability by the protection from burn-out of the conductive filament. The unit sheath is preferably adapted to a glow plug 10. A protective envelope 1 of ceramics high in density includes a...http://www.google.fr/patents/US6040519?utm_source=gb-gplus-shareBrevet US6040519 - Unit sheath
