The box consists of a main compartment holding the plates and a smaller compartment able to hold a pair of plates in their metal holder. A draw-slide separates the two compartments, when this is withdrawn a plate holder drops into the smaller compartment, the draw-slide is replaced. A double dark-slide is attached to the smaller compartment with its draw-slide removed. The plates in their holder fall into the dark-slide when the bottom draw-slide of the transfer box is withdrawn. The exposed plates are returned to the other side of the box.