This buyer bought transistors (difficult to find) and chose non-tracked Postage that was offered to him. He accepted the condition that he is responsible should it go missing provided I supply an official "Proof-of-Postage". A few days later, he filed an Ebay case claiming "item not received", demanding a refund, without contacting me first or requesting a replacement. He would not reply to emails, answer any question or respond to the case. These devices are not available anywhere else and cannot be substituted. I discovered that he has done this many times to other sellers. I asked Ebay to do something about it but they do not seem to be genuinely interested or care.