Many sellers do not use any form of tracking on purchases.
It can be very expensive - $25 or more- to do so directly through USPS. This would be the First Class International service.
However, this is not a problem for a buyer.
First, eBay and Paypal have a strong Buyer Protection program. If your item has not arrived within 20 days*, come back to this question and we will show you what to do next.
Second, if the item has been mailed, it is vanishingly unlikely that it will not be delivered. I speak from nearly 30 years in mail order selling everything from wood stoves to high value postage stamps.
Third, if you are not home when your purchase is delivered, the postie will leave a notice in your mailbox telling you where and when you can pick it up. You will be asked for identification, for your further security.
*The deadline for complaints is longer than that, but 20 days is plenty for delivery from the USA. From Asia, 30 days is enough.
