This is a universal Licence plate bracket. It would be made to fit a wide variety of sportbikes but does not have a specific application. Likely it could be easily adapted to use on your Kawasaki Ninja 250R.
Need to find out in description say that no turn signal mount, but on the display picture it look like there are 2 holes each side left and right seem like for the turn signal to be place. Please clarify before ordering