SanDisk 256GB Ultra Dual Drive m3.0, microUSB and USB Type-A, High-speed USB 3.0, Retractable design for Android Devices and Computers - SDDD3-256G-G46

If you noticed the picture of the packaging, there are two asterisks aka a catch. On the back of the packaging it reads: **Reads speeds from drive to computer up to 150MB/s. Write speeds lower and varies by capacity. USB 3.0 port required. Based on internal testing; performance may be lower depending upon host device.This isn't an issue for me as one cannot expect every device to perform as advertised. There will always be a limiting variable preventing you from ever reaching max advertised speeds. People need to understand this. Your old Galaxy S3 micro USB port (for example) will not push this drive to its limit. Onto the write/read speed test using H2testw.Using this drive on a USB 3.0 port and H2testw I was able to reach a peak of ~55MB/s write speeds at the start of the test. However that didn't last long and the drive steadily slowed down to 27.9MB/s 10min into the write test. At 1 hour, 25.7MB/s. When verifying the written data the drive peaked at 141MB/s. By the end of the test the drive stabilised at 103MB/s. I believe the drops are caused by thermal throttling of the drive, as it did it hot to the touch during testing.Please note, this isn't real world performance. H2testw is writing very large files, one at a time. Transferring photos will not reach these speeds as they are small files, the transfer speed will peak then drop back to zero before peaking at the next file. Transferring videos is similar to the test, as they are large files where the drive can ramp up to it's max possible speed. Again, depending on the host device and many other variables.H2testw is a free Windows utility that verifies the true capacity of the drive by writing "dummy files"; writing until the drive is full or "full". Then the utility reads them to verify the files, ideally the verify will complete without error. If it ends with an error it will show at what amount it ended. For example, if it ended at around 16GB but you purchased a 128GB; this simply means you received a counterfeit drive and should return the drive. If the test ended on an obscure number, the drive is faulty and needs replacing.The drive I received passed with a final capacity of ~117GB for the 128GB model. This is normal as some space is taken up by the MBR, the "library" of the drive where all your files locations are kept. This is how the host device knows what goes where, what is empty and what is not.There are two files already on the drive, a PDF manual and a APK file of SanDisks app for Android. I don't know why they bother including the APK as Android users would have to enable "Install from unknown sources" in their device settings. Just search for the app in the Play Store if enabling this makes your weary, although you can simply disable it right after you install the APK. But again, there's no point in the first place as the included app is probably outdated and will be updated by the Play Store soon after.

This little flash drive is a lifesaver for getting files from my computer to my phone so easily! The MicroUSB and USB 3.0 dual format is so convenient—I can back up photos from my Android and get them onto my laptop in seconds. Speeds are decent, and I appreciate that it's small enough to throw in my bag without having to worry about it. The sliding mechanism feels a bit flimsy, but as long as you’re careful, it does the job. Overall, it’s a handy, affordable gadget that makes file transfers way easier!

Worked

This is a great device for significantly increasing the media storage available on an Android device that doesn't have it's own removable memory slot. It also folds up extremely small, making it easy to carry and not in the way when plugged-in to your device.I own and love an Amazon Fire HD6 but find I am constantly fighting its memory limitations (only 8GB net of the operating system) when I travel.With this device I just create a personal library of my personal digital content (pictures, videos, mp3, etc by copying it from my computer, using the standard USB plug -- just like any USB flash drive -- and if you have a USB 3.0 port the transfer is very fast. Then, when I want to watch content not available online I just plug the micro-USB side into an Android device and access all the content.On the Fire HD6 I first needed to load a File Manager App (I used ES File Explorer) to access the files, and that enabled me to watch videos with any media player I had available (of which there are many - I've been particularly enjoying MX Player and VLC Player). I can also copy content from the drive to my device's memory (in the DCIM folder) which enables me to access it without the USB drive attached. This is useful on a long plane ride when you will probably need to plug a charger or external battery in at some point while still watching content. And you can copy content from the device to the drive and then remove it from the device to free up space.Note -- the only thing I haven't been able to make work is using the device for application-integrated content such as downloaded videos in Amazon or Netflix or downloaded music in Amazon Music. I can neither figure out a way to get my device to recognize the drive in order to directly download the content to it (as is possible with integrated expandable microSD storage), nor to work if I copy downloaded files from the device to the drive, to temporarily free up storage (I tried this once but it messed up my device's internal accounting of available storage so I had to re-initialize the device.). However, this is a minor issue -- I have more than enough personally owned digital content to provide an wide variety of entertainment while traveling unconnected or otherwise poor wifi connectivity (as I've discovered can occur during peak holiday times even in places with usually good connectivity when everyone is trying to use them to watch videos).I recommend purchasing the largest available version (256GB) so I don't have to think about which content to take in advance -- I just maintain a fairly large library of videos and music for use whenever the occasion arises.

Great purchase!

I have several of these because I had to seriously clean up my phone on photo storage. Problem is with some of the more recent ones I got. It now takes time for photos to pop up on app or if I don't click onto one of my transfer files of the thumbdrive, it will just drop them in and then you have to transfer them again to their designated file. Also problem with cost of these, will vary widely. Last only one that was available, cost me almost $10.00 vs. the under $7.00 price available right now (December 29). Will get pretty warm too, if left plugged in too long. Because of size, have a designated space or storage for these because small size makes them easy to misplace.