THE SPANNER IS 8.3/4 INCHES LONG OVERALL.

IT IS INSCRIBED, 1/2   BSA   NO. 10   9/16,   (I BELIEVE BSW  WHITWORTH).

IT IS ALSO INSCRIBED AT THE LARGER JAW END, "BSA"   PLUS  THE BSA TRADE MARK,   "PILED ARMS".

PLEASE STUDY ALL THE PHOTOS AS WHAT YOU SEE IS WHAT YOU GET.