The description is quite confusing - it says at same time class 10, which means that you should not expect write speed higher than 10mb/sec, and at the same time, it says UHS-1, which means 30mb/sec write speed. The truth, as usually, is somewhere in the middle, but close to lower end. I have a dedicated, high speed PCI-E cardreader, which I use for chip benchmarking. So, this card showed 12mb/sec sequental write speed and 34mb/sec sequental read speed. So, UHS-1 is "true" only for read operations, meaning that if you wanted this card to speed-up your digital camera speed photography - you've made the wrong choice. Just for reference, this cardTranscend 16 GB Class 10 microSDHC Flash Memory Card TS16GUSDHC10has sequental write speed of 17mb/sec and sequental read speed of 24mb/sec. As you see, the cheaper transcend has average 40% faster write speeds!