I am currently havin 64gb samsung class 10 micro sd card which is very fluent in use. It can transfer 1gb data in 3 minutes . It is unbelievable , its downloading speed is 48mbps which is marvellous , just believe me if you want to purchase you can , I was little bit confused about sd card , then I decided to ourchase samsung and it is working excellently , no problem for me and I loved it so much. Thanks