Invalid serial number

Two things:

1. Mac Jim ID already covered this, but using this link does not work for every Apple product. There are a few accessory items, like power adapters, that cannot be checked using it.
2. You can try using these Apple Support articles to provide you with some details, but they in themself, cannot verify an original, nor fake product:

• • Power adapters for iPhone - Apple Support
  • About Apple USB power adapters - Apple Support

The only way you would know for sure is if it is purchased from Apple or Authorized Apple Seller. The counterfeit market for Apple accessories is huge and when purchasing outside of those channels, there is a high percentage chance that they are fake. Not only do they fake the cosmetic appearance of the device with labels that look legitimate, they can also include serial numbers of devices that are legitimate. There is no foolproof check that you will be able to do that will determine if they are original.

Mr_abdulrahman wrote:

Okay i will check the product

As stated there is not check you can do that will determine if it is legitimate. The only way that is determined is if it was purchased from Apple or Authorized Apple seller.