The present disclosure relates an elongated housing for an injection device for delivery of a liquid medicament, the housing comprising:a tubular-shaped cartridge holder to accommodate a cartridge filled with the medicament and comprising a proximal connecting end,a body to accommodate a drive mechanism operably engageable with a piston of the cartridge, wherein the body comprises a distal connecting end connectable to the proximal connecting end,wherein one of the proximal connecting end and the distal connecting end comprises an insert section,wherein the other one of the proximal connecting end and the distal connecting end comprises a receptacle to axially receive the insert section,wherein the insert section comprises at least one fastening element to positively engage with a complementary-shaped fastening element of the receptacle to provide an axial interlock of the cartridge holder and the body,wherein the fastening elements of the insert section and the receptacle comprise at least one pair of a radial protrusion mating with a radial recess provided on an inside wall of the receptacle and on an outside wall of the insert section andwherein a radial depth of the radial recess is smaller than a thickness of the sidewall of the insert section or a thickness of a sidewall of the receptacle.
