A new American $100 bill designed to thwart counterfeiters will finally enter circulation this week after years of delay thanks to "production challenges".
The new notes - which took more than a decade top develop - include a blue 3-D Security Ribbon on the front containing images of bells and 100s that move and change from one to the other as you tilt the note.
Another new security feature is "The Bell in the Inkwell", which changes colour from copper to green when the note is tilted, an effect that makes it seem to appear and disappear within the copper inkwell.
Unveiled in April 2010, the $100 bill was slated to enter circulation in February 2011 but printing issues saw some notes creased while others had their ink smeared.
Finally, with "challenges resolved" and enough notes ready to hit the streets, the Fed will begin sending the bills to banks on Tuesday. Old $100 bills are still legal tender.