What is the transparent film that covers water-soluble dishwasher tablets?

These dishwasher tablets ([Finish Powerball Shine](http://www.finish.co.uk/shine-and-protect/)) seem to be covered in plastic!


[![Film-covered dishwasher tablets](https://i.stack.imgur.com/HExHS.jpg)](https://i.stack.imgur.com/HExHS.jpg)


But that can't possibly be true since there's no unwrapping, and they're completely soluble in water.


What is the film made of? 




It is made using Polyvinyl Alcohol (Mowiflex material).


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