triangular (base is app. 20 mm, sides ca. 14 mm) with protruding pocket for insertion purposes (overlap is 8/11 mm), embossed (4 different patterns), made of matte paper (black photo corners), made of glossy paper (mixed colours), or, alternatively, of semi-gloss paper (in the case of other photo corners), is self-adhesive on the back (glue is solvent-free and acid-free)