From Linlai website, Buyer Beware:
https://linlaiglobal.com/index.php/category/buyer_beware/
This is particularly interesting...
Chinese domestic tube market, unfortunately, is very much unregulated with insufficient trademark protection, a very chaotic supply chain dotted by ‘underground or backdoor deals’, sometimes even mixed with counterfeits and bad qualities. We do NOT know all. Our business is to supply quality tubes through our own operation and reseller network.
Each authentic Linlai tube has a serial number.