For those concerned about counterfeit ZWN, check for two vertical rows of small marks (sort of semicircles). These are on the front in the light blue box to the right of the rocks and on the back in the light blue box to the left. Hold the note up to the light to see if the circles match perfectly to form 100,000,000,000,000. This security feature is difficult for counterfeiters to duplicate with a perfect match. Also, look for a metallic strip to the left of the rocks on the front of the note. Turn the note slightly sideways to see the metallic shine. At first glance, it might not appear to be metallic.