for auction is an unusual  back plate  It measures 9 7/8'' long. it measures 2 3/4'' wide at the widest points. It has hammered edges The spirals are strong and sturdy.  They have some flex, but there is no danger that the spirals could loose their round  shape.  There are no makers /manufactures marks.   The material for the back plate is a strong 1/8'' thick. At the spirals the metal gets thicker towards the centers of the spirals  to give a 3 dimensional look to it. I do not know how old it is. I do know the person who had it, Picked it at an estate auction some 50 years ago.   Please see all pictures for condition. Ask questions before you bid. Any information will be appreciated.  Buyer pays shipping with delivery confirmation usps ground advantage. thanks for looking.