This is a bell that was previously attached to a Brompton. It is a genuine manufacturer's product. It's an older version and can be mounted on either the left or right side of the current brake levers. (The current version has a larger bell and can only be mounted on the right.) It's small (the bell is approximately 26mm in diameter), so it's discreet and simple. It is no longer in circulation, so I think it's a valuable item that's hard to find. The package is unopened and comes with the instruction manual.