Abstract: A medication delivery device is provided and comprises a housing, a plunger within the said housing, a plunger hook, and a button, the button connects to a safety sleeve, disengaging safety sleeve from the plunger hook, thereafter the button engages with the plunger hook to push release the plunger held under spring pressure. The device further comprises a shield lock member to connect a pre-filled syringe (PFS) holder and a needle shield together. The shield lock member is activated after the dose is delivered.