An electronic device having one or more contact posts is disclosed having a sleeve slidably mounted around the contact post and lockable by a push-push latching system in a retracted position in which the sleeve is below an upper end of the contact post and an extended position in which the sleeve extends around and covers the upper end of the contact post. The sleeve and contact post may have respective apertures extending transversely therethrough, which are aligned when the sleeve is slightly retracted to receive a probe. Alternatively, an ECG electrode clip may engage an end of the contact post when it is exposed by the sleeve being in the retracted position.