Arrived in time as stated. Micro-SD cards are working. But it said 30Mb/s writing speed. I trasferd 4Gb of data to one of the sd cards, using the laptop's sd card slot. I checked the speed during file transfer. It reached about 27Mb/s at a few instances. Most of the time it was writing at speed of about 200Kb/s. So the writing speed was changing from about 50Kb/s to 27Mb/s. I am not sure whether this speed change due to the nature of the file.