Sales packing of the blister type

A sales packing of the blister type and of the kind comprising a backing plate (2) having undercut side edge recesses (12) for receiving and holding opposed edge flange portions (8) of a domed front cover (4), characterized in that the backing plate (2) along at least one edge thereof is additionally provided with protruding edge flange means (24) operable to be received in a said undercut edge recess (12) of a similar backing plate of another corresponding packing by insertion of the edge flange means (24) for edgewise joining the two backing plates as separate elements perpendicular to each other, such that four similar backing plates are joinable into a square tube element, said backing plates (2) further having at least at one side thereof a number of ribs or grooves (26,27) extending parallel with the backing plate side edges in such a manner that these ribs (26) or grooves (27) of opposed inner walls of said square tube element are operable to support the said opposed edge flange portions (8) of one or more of said front covers (4) to enable these as separate elements to be mounted in a drawer-like manner in the square tube element.