I am 100% its authentic genuine Hiwin rails otherwise I would never have shared the link. My friend ordered two sets of them and he invited me to install theme the same day he got them. They were wrapped with Hiwin original package (exactly the same as at my local authorized supplier) with numbers engraved on the carriage and logos on the rails. All the rails were smooth as hell but we added some oil. I had to run them fast a few times before i installed them. Don't test them by gliding down vertical - its a real test (i wrote it specifically in the rails section). if your carriage glides down almost too smoothly on a vertical motion vibration could affect your print quality). the test should be done horizontally and it should move without any resistance. if you do have some resistance i would advise you to clean them a bit and re-lubricate.Update: I just had a chat with the seller about your feedback ( i sent him a screenshot because I have zero tolerance for scams) but he told me that he got no messages about a problem from any customer about the rails, additionally no negative feedback on the item. I apologize but if this is some kind of stores/sellers/competitive war please leave it out of my project. I just noticed your profile - almost nonactive profile (0 share, 0 follow, 0 likes, 0 collections, 0 makes..).