At Gray Kingdom we can assure all items we stock are 100% genuine.
Manufacturers often make changes to their watches so please don't get confused with slight updates. Most of these updates can be found online.
If you purchase your item from us and it is not directly on the site, we sometimes sell the older versions there as we have more room on pricing.
We have placed some images below to show the slight changes made by manufacturers.
If you look at the two images of the MK5491 you can see slight changes made by the manufacturer. The older version on the left has thicker chronograph rings to the new model on the right. Also the newer MK5491 on the right has thin rings inside of the chronograph which the older version does not have.
You can see here that if you search online for the MK5491 it will mostly bring up images of the left image however if you go into a authorised dealers shop you will see they will more than likely stock the right image.