An injection device is provided herein comprising a container body for holding medication content having a distal end and a proximal end, the container body providing an outward flange at the distal end and a ledge at the proximal end； a piston placed at the proximal end of the container body for sealing and displacing medication content； a push rod placed inside the container body for moving the piston distally； and a connector providing an orifice for medication content delivery, placed at said distal end of said container body. The orifice in the connector provides medication content injection fluid pathway. With modification of the fundamental structure, a number of innovative device designs are created.
