'''Scanners''' (or '''multi-scanners''', or '''Auspexes''') are [[Imperial]] short-ranged devices used to detect motion, invisible gases and energy emissions throughout a wide spectrum, such as heat, radiation and most forms of energy given off by vehicles and living troops. Their main tactical use is to reveal otherwise hidden troops and allow them to be fired on. The standard range of a scanner is fifty metres, although walls more than fifty meters thick as well as certain shielding materials are able to block them.¹