Hello.
I used a 1 year old 16gb class 4 on my new Note 3 for 6 months until it started to fail. I thought I had bought a class 10 or uhs 1 Samsung card when I got the phone
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I think you would notice a small transfer speed difference with heavy files like video or 4k, or a large amount of data.
I think cards have overtaken the speed of the phones.
You wouldn't notice any problems with a class 10 in everyday use.
The warning goes out again for poor cards on the market. It is safest to go with a genuine official, not branded, Samsung or SanDisk card as they make their own.
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