https://trc-images.nl/collection_images/hires/2018/2018.1453a-b.JPG#\\TRC-SERVER\TRCSharedWork\TRC Database\collection%20photographs\2018.1400\2018.1453a-b.JPG#
Pair of round black plastic buttons with domed shape at back creating a passage to be sewn through as attachment. Linear pattern on surface created in moulding process.