Ever noticed the colourful shimmer of the bird in the clear window of New Zealand's dollar notes or the clear black and white replica of your face in your passport?
That technology is called the Kinegram and it is just one of the ways New Zealand protects itself from counterfeiters and fraudsters.
Stephen Pratt, managing director of Kurz in Australia - whose parent is a privately owned German company - is the company behind the technology which is also used in the Australian, Canadian and Euro currencies.
Pratt has been working with the Reserve Bank of New Zealand since 2013 on the development of the latest banknote with the $5 and $10 notes going live in October 2015 and the $20, $50 and $100 released in May 2016.
The technology has been used in the New Zealand passport since 2010.
Pratt said Kurz purchased OVD Kinegram in 1999.
"It was technology that had been discovered as part of another process."
It was commercialised and sold to governments for important documents.
Pratt said the technology was not available in the wider market and that was one of its stronger selling points.
"The second thing going for it is the technology has only ever been sold to governments."
Pratt said the Kinegram worked because it was easy to verify and easy to see.
"It is not like a hologram which is the other technology widely used."
Kinegrams can be made in distinct colours, a line pattern and monotone. It is the fine line structures that make it unique.
But while it was easy to identify it was "impossible" to copy, Pratt said
Counterfeiting is rare in New Zealand but does still happen.
Figures from the Reserve Bank show in the 2017/18 year New Zealand had just 0.8 parts per million counterfeit notes in circulation.
That compares to Australia's 16 parts per million notes and the United Kingdom's 127 parts per million notes.
Since 2004 New Zealand has ranged between 0.5 and 3.4 which was hit in 2011.
Earlier this month counterfeit $50 notes turned up in Christchurch.
Steve Gordon, the Reserve Bank's head of banking said at the time that New Zealand's banknotes and coins were among the most secure in the world, and counterfeit rates were extremely low.
"We typically see one or two fakes a month hit the banking system, and the last time we had a counterfeit spate like this was in Palmerston North a year ago."
Pratt said counterfeiters often used cellophane or silver foil to try and trick people and notes could be missed when hidden in a bundle.
"Most notes get picked up by a bank or note sorter then handed to police.
"There are definitely shop-owners that pick them up but it is generally later in the day.
Pratt said the move into polymer based notes which happened around 20 years ago had reduced counterfeiting significantly and it was no longer carried out by organised crime groups.
The Kinegram was only one of a number of measures designed to protect the currency.
How to pick a counterfeit note:
Check out the windows
Inside the large clear window is a hologram featuring a fern and a map of New Zealand. It also contains the same bird featured on the left-hand side of the note. There is also an embossed print denomination below the hologram.
All washed up
Polymer notes and their inks are water resistant. There should not be any blotches or running of the inks.
Get out the glass
Tiny micro-print of the note denomination should be visible with a magnifying glass. On the large numeral, the letters "RBNZ" are in microprint. On the front of the note, the foil inside the window reads "RBNZ 10 TE PŪTEA MATUA 10". On the back are the numbers "10101010..." and "RBNZ", between New Zealand and Aotearoa.
Feel for real
Polymer notes have raised printing, which can be felt when you run your fingers over it.
It's a serial
Each note has an individual serial number printed horizontally and vertically and these numbers match exactly. If the serial numbers are missing, or if you have several notes with the same serial number on all of them, some or all of those notes could be counterfeit.
Does it glow?
Most commercial papers used in forgeries glow under an ultraviolet light, but our notes use special inks which look dull except for specific features that glow brightly. For example, the front of each genuine note includes a fluorescent patch showing the denomination.
No to fuzz
All images should appear sharp and well defined – not fuzzy and washed out.
Check for the change
The colour of the bird changes when the note is tilted, with a rolling bar going diagonally across.
Line it up
When the note is held up to the light irregular shapes on the front and the back of the note combine like puzzle pieces to show the note's denomination.
Rip into it
Polymer notes are tough, but most counterfeits are only paper. Moderate force should not start a tear in the note.
What should I do if I find a counterfeit note?
If you believe someone is trying to pass you a counterfeit note, do not accept it, and notify the Police.
If you find you've already received a counterfeit note, put it in an envelope to avoid handling it further and take it to the Police.
Source: Reserve Bank of New Zealand