I bought this oxygen generator- it arrived in good packaging but is in Chinese (although a cover note asking if I wanted an English copy of instructions contact their email The issue is it knocks loudly (like a loose piston) I have contacted wish and the supplier has requested more info and my email that was 4 days ago and I’m still waiting for a response I’ve never had an issue on wish that wasn’t fixed immediately but then this is the first time I’ve spent a large amount of money - I’m still waiting on resolution [Source : Wish]