It's a bezel attached to a screw. You can easily punch a hole in metal or leather and insert the screw, clip it off and sand a bit to make an attractive bezel attached to something of your liking!
Base Metal: Pewter
Plating: Pure Silver Antiqued
Outer Dimensions: 18 x 15 x 2mm
Inner Dimensions: 12.8 x 12.8 x 1.6mm