If an ebay seller from China lists their merchandise as 100% authentic is this always the case?

It also includes a UPC & MPN number as well. Its just an expensive item for very cheap listed as brand new unopened. Here is a link.

www.ebay.com/itm/121012823880?ssPag...

Thanks.

If its from China, 99.9999999999999999999% of the time its a fake, no matter what the seller says