Leica Helical focusing mount #4068 ZOOXY for Elmar 5 cm lens

this item appears in the 1954 Leica catalogue - in order to use it you must have a E39 screw mount Leica camera and a 5 cm Elmar lens.  The lens focuses from 1 1/2 feet to 9 inches. This item weighs 12 ounces and is very strong.  The photos show how it changes length as it focuses. (Additional equipment is required to use this item, it cannot just be focused using only  on a screw mount body and Elmar lens.)