A sub-assembly of a medicament delivery device

A sub-assembly of a medicament delivery device, the sub-assembly comprising:

• a housing extending along a longitudinal axis between a proximal end of the housing and a distal end of the housing;
• a delivery member guard telescopically arranged within the proximal end of the housing;
• a plunger rod axially movable along the longitudinal axis within the housing, wherein the plunger rod is configured to move into a medicament container;
• and
• a plunger rod driver comprising a driver body having a flexible portion, wherein the flexible portion is positioned between the housing and the plunger rod in a direction transverse to the longitudinal axis, wherein the flexible portion is radially flexible relative to the longitudinal axis,
• wherein the plunger rod driver is configured to couple to a power source that is configured to move the plunger rod driver in the direction of the longitudinal axis relative to the housing from a distal position to a proximal position,
• wherein the plunger rod driver engages with the plunger rod and does not axially engage with the delivery member guard when the plunger rod driver is in the distal position, and
• wherein the flexible portion is configured to be flexed radially outward relative to the longitudinal axis by the plunger rod when the plunger rod driver moves from the distal position to the proximal position so that when the plunger rod driver is in the proximal position, the driver body axially disengages from the plunger rod and axially engages with the delivery member guard.