https://trc-images.nl/collection_images/hires/2018/2018.1442.JPG#\\TRC-SERVER\TRCSharedWork\TRC Database\collection%20photographs\2018.1400\2018.1442.JPG#
https://trc-images.nl/collection_images/hires/2018/2018.1442_2.JPG#\\TRC-SERVER\TRCSharedWork\TRC Database\collection%20photographs\2018.1400\2018.1442_2.JPG#
Square red disc button with a 'well' at the centre enclosing four sewing holes.