HEATING: Even with just 10 minutes of use, you can touch and feel that the metal part of the pen drive is getting heated. But the performance of the drive has not got affected by the heat. This heating does not happen in WD external hard-disks and seems to be unique to small pen drives of various brands. Benchmark Crystal Disk mark scores for a file transfer of 500 MB size were 34 MB/s -Read & 19 MB/s – write which looked like a mere consolation. Transfer between my Samsung S7 mobile & S2 tablet too was not fast. MOBILE PHONES: The pen drive works with Android OS of Mi phones such as Redmi Note running Android including old Android Version 9 as well. I admit I have a USB 2.0 port at my laptop yet I was never used to such low speeds ever. The tagline “Ultra” and mentioned speeds of 130 MB/sec (which I suppose is the rated max. speeds at USB 3.0 ports) felt like a dream and beyond exaggeration. But For Example, If you have decided that you won't use it on mobile phones or tablets because the fitting is too tight and you don't want to risk damage to this point which is primarily used for charging - then go ahead and format the pen drive for your laptop.

Even for a single movie of 1.8 GB it took 2 minutes 30 sec by stopwatch to transfer. The write speeds started with 13 MB/sec and went down & down to 10-11 MB/sec. Even with my older Kingston DT elite 3.0 16GB,the write speeds were in excess of 21 MB/Sec. Blazing transfer speeds lets you offload cards fast. Use with the SanDisk® MobileMate® USB 3.0 microSD™ card reader 6 to achieve up to 150MB/s speeds 2. SAME AS OTHERS: For the 64GB pen drive, actual storage space available is 57.2GB. This is normal and not some fraud or fake advertisement. This is because it has FAT32 File System. Also, the device uses some space for its functionality and use. With a micro-USB connector on one end and a USB 3.0 connector on the other, the drive lets you move content easily between your android phones, tablets (with micro USB ports only) or laptops.

Customer reviews

With your Linux system's file format, you will have better storage space than any Windows File System. STORAGE : Out of the total name plate rating of 64 GB , the actual allocated space for usage is around 57 GB which is ok enough. A1 performance is 1500 read IOPS, 500 write IOPS. Based on internal testing. Results may vary based on host device, app type, and other factors. SanDisk Ultra® microSDHC™ and microSDXC™ UHS-I cards are compatible with Android™ smartphones and tablets, Chromebooks, and Windows® laptops. Just insert the card to instantly increase available storage space—at a great value relative to alternatives. New Windows® convertible and ultra-light laptop users, in particular, who were accustomed to the multiple terabytes of storage common on larger laptops will appreciate cards enabling more private physical storage.

SanDisk Ultra is a brand of Western Digital which is the same company that sells external hard-disk storage devices under the brand WD Elements and WD Portable. SPEED: The Speed is extremely good for Windows OS laptop, Linux OS laptop and Android Mobile Phones. See Western Digital White Paper- Flash 101 and Flash Management. A detailed overview of flash and flash management (August 2018): documents.westerndigital.com/content/dam/doc-library/en_us/assets/public/western-digital/collateral/white-paper/white-paper-sandisk-flash101-management.pdf

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BEWARE that if the pen drive has NTFS File System then it won't work with mobile phones, tablets, laptops which don't have Windows Operating System. Same way, if you format the pen drive for Linux OS File System, it won't be recognised on Windows laptops, Android phones, tablets, etc. Finally with every passing minute it became all the more unbearable and annoying. Even in NTFS format speeds were the same. I had never expected it to be this slow in this modern era of 2018, thus finally I decided to return it but I suppose I will only get a replacement & not reversal. TOO TIGHT FOR PHONES: The pen drive is a tight fit on mobile phones & tablets - so be careful when pulling it out so as to not damage your phone - because this is also the charging point for your phone. If you feel that your phone is too tight for this pen drive, then it is best not to use it for phone data storage management.