Cast Iron 139A payphone mounting stand or bracket made by Gray. Your old 3 slot payphone mounts to this cast iron mounting stand. That way you have a table or countertop mounted payphone.  I remember as a child that Woolworths  store in Milwaukee WI  had a few of these mounted to the counter in their restaurant  And Goldman's department  store also had one mounted to the counter in its restaurant. Very rare original item. We have the special mounting bolts for $12.99 if you need them.