An implantable penile prosthesis system comprising a penile implant comprising a proximal portion implantable in a crus penis, and a rear tip extender, with the proximal portion of the penile implant comprising: an annular groove formed around a circumference of the penile implant to define a groove diameter, a tapered section proximal the annular groove, with the tapered section having a continuous reduction in diameter from the annular groove toward a proximal-most end of the penile implant, characterised by a neck groove formed in the tapered section between the proximal-most end of the penile implant and the annular groove; and the rear tip extender forming a cavity sized to receive the proximal portion of the penile implant, with the cavity defined by an interior wall provided with a plurality of locks comprising: a distal lock formed as an annular protrusion extending radially inward away from the interior wall of the cavity, where the annular protrusion is sized to engage with the annular groove of the penile implant, and a proximal lock formed as a wedge-shaped tooth extending radially inward away from the interior wall of the cavity, with the wedge-shaped tooth sized to engage the neck groove of the penile implant. a penile implant comprising a proximal portion implantable in a crus penis, and a rear tip extender, with the proximal portion of the penile implant comprising: an annular groove formed around a circumference of the penile implant to define a groove diameter, a tapered section proximal the annular groove, with the tapered section having a continuous reduction in diameter from the annular groove toward a proximal-most end of the penile implant, characterised by a neck groove formed in the tapered section between the proximal-most end of the penile implant and the annular groove; and the rear tip extender forming a cavity sized to receive the proximal portion of the penile implant, with the cavity defined by an interior wall provided with a plurality of locks comprising: a distal lock formed as an annular protrusion extending radially inward away from the interior wall of the cavity, where the annular protrusion is sized to engage with the annular groove of the penile implant, and a proximal lock formed as a wedge-shaped tooth extending radially inward away from the interior wall of the cavity, with the wedge-shaped tooth sized to engage the neck groove of the penile implant. an annular groove formed around a circumference of the penile implant to define a groove diameter, a tapered section proximal the annular groove, with the tapered section having a continuous reduction in diameter from the annular groove toward a proximal-most end of the penile implant, characterised by a neck groove formed in the tapered section between the proximal-most end of the penile implant and the annular groove; and the rear tip extender forming a cavity sized to receive the proximal portion of the penile implant, with the cavity defined by an interior wall provided with a plurality of locks comprising: a distal lock formed as an annular protrusion extending radially inward away from the interior wall of the cavity, where the annular protrusion is sized to engage with the annular groove of the penile implant, and a proximal lock formed as a wedge-shaped tooth extending radially inward away from the interior wall of the cavity, with the wedge-shaped tooth sized to engage the neck groove of the penile implant. a distal lock formed as an annular protrusion extending radially inward away from the interior wall of the cavity, where the annular protrusion is sized to engage with the annular groove of the penile implant, and a proximal lock formed as a wedge-shaped tooth extending radially inward away from the interior wall of the cavity, with the wedge-shaped tooth sized to engage the neck groove of the penile implant.