A medicated module for an injection system to co-deliver at least two medicaments is disclosed where a primary delivery device containing a primary medicament accepts a medicated module containing a single dose of a secondary medicament and where both medicaments are delivered through a hollow needle. The medicated module is user selectable so that it will deliver a priming dose of a primary medicament or both the primary and secondary medicaments. The module also contains a needle guard that locks after dose delivery. The needle guard prevents accidental needle sticks before and after an injection. A locking collar rotates during use as an inner protrusion follows three paths of a track located on the outer surface of a body housing. When the inner facing protrusion is in the third path, it encounters a hard stop and a rotational bias that locks the guard from further refraction and thus covers the sharp distal end of the needle.
