Tim,Each end has a spring loaded cover. The spring is down one side of the body of the charger and is common to both ends. Can send some pics if you want.
Not to steal anyone's thunder but Mike Lea usually has a few available.
Does anyone know how these are made (i.e. the body with a taper in both directions) ?? Would love to make a few but would want to know how they were originally done before i waste a lot of time trying to figure it out for myself...