I bought a one for my gl500 5 years ago-sight glass became useless so JB Weld over it . Been a year & no issues .PaulThe problem with master cylinders from Chinese eBay sellers is that some are great and some are garbage and you can't tell from the pics or the price.
I fell into that trap some years ago when I bought 2 to replace the ones on my bikes. I installed one on Eccles right away but before I got around to installing the other one on Mr.H the first one failed.
I bought 2 more from an eBay listing that a knowledgeable forum member posted a link to and they have held up well other than the sight glasses eventually soften. But replacement sight glasses are cheap and easy to install so I don't mind doing that when I replace the fluid every few years.
These days we usually recommend buying from one of the known places like DSS or at least from a US eBay seller.