This is a quick word of advice for everyone buying fast (Class 10 or more) SD cards off ebay, using personal experience.
Currently (2011), large capacity SD memory cards are becoming popular with the demand in HD Video cameras, and are quite expensive. It is advised that you purchase the fastest card possible (ie Class 10 or more) so that the video camera can read and write the capacity-hungry HD video files with ease. There are plenty on ebay, so the motion is usually to check ebay first for a cheaper deal before buying from the high street / online stores.
However, there are many ebay sellers, sometimes operating abroad, who are selling SD cards as "fast" classes, which turn out to be fake and slow. They still work fine as a storage card, but to the average punter it is easy to believe that it is a class 10 (which you would pay a premium for) when it is in fact a class 2 or 4. I found out the hard way, and after testing my purchases in the video camera and with testing software, it turned out they were fakes and I returned them all. I sometimes had to fight to get a refund, but other times the seller didn't deny the fact it was a fake, thus giving away the fact they KNOW its a fake and are just chancing it, as how would the average person spot a fake?
SO, if you're thinking of purchasing from an ebay source, or thinking of selling Class 10 SD cards and aren't sure whether they are fake or not, heres what you do...
Firstly, check the card's appearance. Cheaply-printed labels are often a giveaway, and sometimes don't have the (10) mark to show it's a class 10. Genuine cards sometimes have metallic/hologramatic labels printed, bearing the class 10 symbol. Serial numbers printed onto the card itself are also a good pointer for a genuine card.
However the ultimate way to tell is to test it using read/write speed software. "H2testw" is a free and easy-to-use piece of software, available on the internet (google it) for testing memory card speeds and capacity. Once downloaded, you may plug the offending SD card directly into the PC or connect your video camera (with the card inside) to the PC and test it from there.
A true Class 10 should be able to read and write in excess of 10mb/s, they sometimes vary depending on the quality, but it should be at LEAST this speed (some are able to read/write up to 18mb/s). If you find the card is performing at 2mb/s, this is indicative of a cheap Class 2. 4mb/s, a Class 4.
If you have purchased a card recently, and find it is under-performing, send it back and demand a refund with the H2testw results (perhaps in a screenshot) as evidence. Some sellers are not aware they are selling fakes, so show a little diplomacy, however the sellers who know they're selling fakes usually give you an outright refund as soon as you sniff something in the air.
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