Her er forklaringen på den brune ring. Det har ingenting med varme at gjøre.
https://www.ngkntk.co.uk/index.php/techn...ono-stain/
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https://www.ngkntk.co.uk/index.php/techn...ono-stain/
https://www.google.com/search?client=ms-...j7rLxTo%3D