Abstract: For emergency use on a highway there is provided a kit containing a collection of parts in disassembled state but ready for assembly within the confines of a small space no larger than the interior of a conventional automobile and then mounted for visual inspection on the exterior. The kit is one comprising a post for supporting a relatively large signboard. The signboard in turn is provided with aligned spaces for reception of individual letters and numbers selected from a reservoir of multiple letters and numbers to spell out a message visible by passerby.