vertical strip of three, imperforate horizontally except at bottom, large part original gum, light crease at center and staining on reverse of bottom stamp, very fine and attractive, originally 20 error pairs were created when one pane was produced missing the top five rows of perforations, but apparently most of these were used as only three mint pairs with top selvage and two strips of three with perforations at bottom are known, ex-Plass, 1994 Philatelic Foundation certificate (Scott $2,250 for pair)