The present invention relates to a medicament delivery device comprising a generally tubular distal housing part (10； 110) having opposite proximal and distal ends, wherein third mechanically coded interface means (11； 111) are arranged on its proximal end； a generally tubular proximal housing (20； 120) part having opposite proximal and distal ends and being releasibly connected to said distal housing part, wherein with fourth mechanically coded interface means (22； 122) are arranged on its distal end； a medicament container having a slidable stopper, wherein said container is arranged to be positioned within said proximal housing part； a plunger rod (60； 160) arranged within said distal housing； drive means arranged within said distal housing and being operably connected to said plunger rod for driving said plunger rod and thereby said stopper towards the proximal end of the device； wherein said device further comprises an interface member (50； 150) comprising first (51； 151) and second (52； 152) mechanically coded interface means arranged to match and interact with the third (11； 111) and the fourth (22； 122) mechanically coded interface means when the distal and the proximal housing parts are connected to each other.
