When employing diary-HIs 4-7 as photochromic components in PMA, robust photoswitching is seen in all cases. Their inherent pronounced photochromism and larger absorption band separation translates favorably into the PMA matrix. In these cases, the very good color contrasts between red and purple remain, allowing to reversibly inscribe information with robust performance into the transparent material (Figure ). The best visible performance was given by diaryl-HI 7, which delivered easily distinguishable contrast between deep red and purple as exemplified in Figure . Reversibility was demonstrated by erasing inscribed information with red light and rewriting new information with green light irradiation (Supporting Figure ).