A circular plug connector comprising: an outer coupling ring having a cavity extending between a front and a rear, the outer coupling ring including a retaining element proximate to the rear, the outer coupling ring including a mating element proximate to the front configured to be coupled to a mating connector; a plug shell extending between a front and a rear, the plug shell housing one or more plug contacts configured to be coupled to the mating connector, the plug shell having a front body at the front configured to be coupled to the mating connector, the plug shell having a rear body at the rear, the plug shell including a mid-body between the front body and the rear body having a rear facing support surface; characterized in that the circular plug connector further comprises a self-supporting compression element surrounding the rear body, the self-supporting compression element extending between a front and a rear, the self-supporting compression element including a spring element at the front, the self-supporting compression element including a retaining shim support at the rear, the retaining shim support being integral with the spring element as a unitary monolithic body, the retaining shim support being received in the retaining element to fix the self-supporting compression element relative to the outer coupling ring, the spring element engaging the rear facing support surface to support the plug shell within the cavity of the outer coupling ring, the spring element being compressible relative to the retaining shim support to allow the plug shell to move axially within the cavity of the outer coupling ring. an outer coupling ring having a cavity extending between a front and a rear, the outer coupling ring including a retaining element proximate to the rear, the outer coupling ring including a mating element proximate to the front configured to be coupled to a mating connector; a plug shell extending between a front and a rear, the plug shell housing one or more plug contacts configured to be coupled to the mating connector, the plug shell having a front body at the front configured to be coupled to the mating connector, the plug shell having a rear body at the rear, the plug shell including a mid-body between the front body and the rear body having a rear facing support surface; characterized in that the circular plug connector further comprises a self-supporting compression element surrounding the rear body, the self-supporting compression element extending between a front and a rear, the self-supporting compression element including a spring element at the front, the self-supporting compression element including a retaining shim support at the rear, the retaining shim support being integral with the spring element as a unitary monolithic body, the retaining shim support being received in the retaining element to fix the self-supporting compression element relative to the outer coupling ring, the spring element engaging the rear facing support surface to support the plug shell within the cavity of the outer coupling ring, the spring element being compressible relative to the retaining shim support to allow the plug shell to move axially within the cavity of the outer coupling ring.