The quality of Seiko is so high it was the official manufacturer of watches for Japanese soldiers during world war II. A small knob on each face will unscrew to open the sides of the clock face to unveil this.
Seiko Double Sided Ships Passageway Clock – Cream
18th Century Colifichet Embroidery On Paper Double Sided Neeedlework C 1790
A 9ct Gold Double Sided Open Locket & Gold Plated Chain, Marked A&C 9ct (F3889)
Pair of 19th C Welsh Language Double Sided Posters of The Lord Prayer, The Ten C