They are made of thin soft matte plastic

this is why

18 of the colors are the same

Pen-Touch Fine marker from Sakura is a permanent and quick-drying marker

Index Highlighter Sticky notes - Ocean Blue Titel:Default Title They are made of thinIndex Highlighter Sticky notes Ocean Blue from Ordinate. Pack of assorted sticky notes. 3 long, narrow strips with post it adhesive, perfect for highlighting text in books, measuring 5 x 135 mm. 3 shorter ones measuring 83 x 5 mm. 1 measuring 83 x 13 mm. 1 measuring 49 x 13 mm and 1 measuring 20 x 49 mm. 20 sheets of each. They are made of PET, a thin, transparent, matte plastic. Semi transparent so you can see the text underneath. Made in Germany.