Mega Brown Box Complaints on OfferUp sold a defective oxygen generator no oxygen not even air the sales rep explain We can change it for the other one if you’d like However i then get second message it reads : Hey, sorry. I just wanted to clarify. We can take a look at the machine and try and explain how to work it, but we won’t be able to give you an even exchange. We looked it it together and I was clear that once the machine left, I wouldn’t be able to sell it as is. If we need to exchange it, I would have to charge a restocking fee of 20 dollars. But we can help you try and figure out how to use it What they talking about straight crooks to avoid