You're looking at a set of ten segma buttons measuring 13mm (0.51) in diameter across the top of the button, with a post length of about 6.5mm but may vary slightly from post to post. These buttons are all metal and quality made in Japan. Excellent for purse flaps, pockets or attaching items.
Simply set as you would a rapid rivet using a setter and anvil (available separately).
Hard to find elsewhere! The background grid represents 1cm square.