I looked on the box the cap came in..............pretty old but it fits Triumph,Ducati & Aprillia........ If I remember eBay seller had a "buy it now" or "make offer" price... There are MANY to choose from. Anodized colors, styles, etc.
BTW........theses are stainless steel fasteners so don't drop any in the fuel tank. A magnet will not pick them up.I know this from experience.