I purchased this micro SD SD card a few days ago, mainly for my smartphone (Axon 7), mainly for storing bulk data, and 4K video.

Performance: For my tests, I am using a UHS 1 USB 3.0 card reader, as it supports the full read and write speeds available in the UHS-1 standard.

For a more realistic performance review, I do a 100% fill, as with some lower quality cards, they may offer high initial speeds, but what happens to some, is that the write speeds may drop by up to 50% once all of the NAND is dirty (around 25-50% filled); this product does not have this issue.

Even if you do not care about the performance, I recommend that you always do a 100% fill on any flash storage that you buy, as the one thing counterfeits are unable to do, is offer consistent write speeds for the entire length of the drive.

The performance is very consistent for TLC NAND storage, with it largely able to remain close to its 20MB/s advertised on the packaging for the entire length of the card (100% fill). This one only has a marginal difference as the drive fills, which points to the NAND being fast enough saturate the storage controller while writing directly to dirty TLC flash. This means that even when the drive is mostly filled, performance will be similar to how it is when empty (only marginally slower).

Read speeds averaged 81.9MB/s, with a minimum of 77.6MB/s, and a maximum of 83.4MB/s
Write speeds averaged 20.7MB/s with a maximum of 22.3MB/s, and a minimum of 18MB/s

Those occasional changes in write speeds are due to the TLC flash being used.

After performing my 100% read and write, I then proceeded to format the card suing my phone, and then transfer some data to the card (23GB of music, photos, and videos). I then ran a benchmark using crystal disk mark. This is to more accurately represent the type of performance that the user will see when there are a bunch of files on the card already, since that is the state that the card will be in for much of its service life.
Performance for all flash memory drops slightly when data is already on the drive, thus I feel this will better represent the experience that the user will have on a day to day basis.

For smaller bursts of writes as done in crystal disk mark, we can see that it is able to exceed its advertised write speeds by a larger amount, while read speeds remained slightly lower than the 80MB/s rating. 4K reads and writes are comparable to many other cards in this price range, and the only real takeaway from this is that these cards should not be used to store applications which rely heavily on 4K reads and writes, as even the fastest UHS 1 cards, will still only offer a tiny fraction of the 4K random performance of even the eMMC NAND found in modern low end smartphones.

Overall, I am satisfied with my purchase, and would recommend the card to anyone looking for some extra bulk storage for their smartphones, as well as any netbooks. The performance is good enough for capturing 4K video. With ample space, there is no need to compromise on the quality of the video you record, the music you save to your device, or the videos you store on your device.

Update 1/28.2017:
The card was working great for a while, and offered good enough write speeds and IOPS to ensure that the camera in the phone would not have to wait on the card, but then the card decided to fail in a very annoying way. It seems that when the card feels that it is having any issue, it permanently places its self in a read-only mode. When this happens, the card cannot be formatted, and files cannot be erased from the card.

To make matters worst, the card has to be mailed in for an RMA like that (not the best if you have a CWM backup of your device on the card).
Overall, I am currently going through the RMA process with them, and will see if the replacement card runs into any issue.

Overall, this is the first model of micro SD card that I have ever experienced failing.

Update 2/6/17:
I received my replacement card, I will keep an eye on how the reliability turns out for the replacement.
I also uploaded some ATTO benchmark results for the card.

Upgraded the capacity of my S7 Edge - only 20GB of the 32GB internal storage is available and I used this micro SD card to increase that. Card showed 120 GB available of the 128 GB advertised. Got sequential write speeds of 16MBps+ using Crystal Disk Mark which is more than enough to keep up with my S7 Edge. Camera performance shows no degradation and no worries about running out of space on my phone when taking pictures or shooting 4K videos. Extremely good value for the money that I paid for it ($37odd), no issues so far in the 3 weeks that I have had it with me.

I just got a Samsung S8 Plus and wanted to get a storage card to go into it. My Note 5 didn't have the ability to use a card so I needed to get a new one. But which one? There are so many out there! I originally wanted a much more expensive card that I saw but I couldn't justify the price. I just want to store pics, music, and apps on the card and everything is backed up to the cloud on one of my computers so I decided on this Samsung 128GB EVO. It wasn't super cheap but didn't break the bank either for such a large capacity card.

It came in retail packaging. A cardboard card with plastic overlay with the small card on one side and the adapter on the other. I didn't have to format this card and it just started to work immediately. I have lots of stuff on there now and it's fast. I downloaded some things to the card and uploaded some things from the card and I found the speed to be great. So far, all is working wonderfully. Naturally, the test of time is the biggest one so I will update if there are any issues as time goes by. Right now. I really feel I mad the right choice and this card fits my needs perfectly.

This was the fastest load (write) ever...

I used the card as storage drive on my Android phone, for pictures, files and all my personal CD library of all my music. Cards seem to die after about a year. Most of the times, this after I go on vacation (airport x-ray machine or other rays from being on a plane)? And are always replaced under warranty.

I seems to have this problem (on XP and Windows 7Pro), where as I load the card with my 40GB of 320kbps MP3 music, the load (write) speed slows, till goes soo slow, the computer times out and errors and complains the drive is no longer available.
This time, this it did not crash. However it did slow to, 1/2 to 1/4 the normal speed near the end? However, it was over all 90%, faster than other cards I've ever used. Normally I have to separate the music in to groups, A-G, H-N, O-S.... etc. This takes most of an 8 hour day to do...

This card though was fine (except the slowing down part)...

Product became corrupted in my cellphone after about 2 months, just after it was returnable. it just stopped working. I am very unhappy. I will not buy a Samsung micro SD card again.

I use mine in a Samsung Galaxy Tab A tablet and, so far, it's been flawless. I've always had great luck with Samsung microSDs and can certainly recommend this 128GB EVO.

is a good micro sd memory card but the write speed is slow and is not suitable for a smartphone if your intention is record videos or take photos , maybe is good for other devices that can use memory card like e book readers or point and shoot cameras of less of 10 Megapixeles but for smartphones like my lumia 950 is slow for save a video on it.

It seemed to be defective. The Micro SD card could be read by Windows as having 128GB, but it was locked to write-only. I used the adapter it came with, I used one of my own adapters, I tried it in several devices, I tried to reformat it with several methods, nothing worked. I've read that this is a built in mechanism of SD cards that are about to die to allow you to save your data before total failure. I'm disappointed that I could get a defective product at this price (around $44), and am now about hesitant about buying Samsung memory again.

Very good card and fast for its price and capacity. Write speed is around 18 MB/s and read speed is around 60 MB/s. It takes around 1 hour and 50 minutes to fill it which is actually pretty good for a micro sd card (not full sized sd cards) (at this price range). Therefore, I disagree with the other reviewer that said that the write speed drops down to crawl. The figures I mentioned above was to fill the whole card and read it all the data written back. Probably the other reviewer got a defective unit, has a slow pc/device or was transferring thousands of really small files.
Also it has relatively good speed for small file transfer for its price range (4Kb from the benchmarks pictures attached).
Its a good idea to check your card if it has the advertised capacity when buying it, with h2testw (google it, it is a simple program that fills the drive and then verifies that everything is ok by reading it), since there are many fakes (probably not on amazon).
A tip for persons who want to use this card for backup: If you have a lot of small files and it totals to many GBs eg 50, add your files to a zip file and then add the zip file to the card. The transfer speed will be significantly faster (more than 20x).
I had that card for around a year without problems. I recommend it.

A genuine Samsung product, which has been test against the h2testw program and confirmed the memory to be 128GB (minus the normal / expected data difference).

The 128GB memory card continues to work perfectly in my Samsung Galaxy S7 mobile phone, I have not had any issues with data freeze, finding data on the card or losing any data. I am really pleased with the product.

I am always very sceptical about buying memory cards having been caught out a few times previously with fake cards. You buy from this seller with confidence as the product is genuine and the memory you buy is the memory you get !!

Update: Feb 2018: I have read the Fake Card review and viewed the 'fake v genuine' comparison pictures submitted as part of the review. Whilst I cannot dispute the reviewers experience or findings, I have just checked my Samsung 128GB card again against those pictures and can confirm the 128GB SD Card and Samsung adapter are both genuine and correspond exactly to the genuine ones in the photos. That said, the fake review is very helpful as are the photos but for clarity my experience was positive and the Samsung micro SD card is genuine.

 Worked fine for a year, then when I went to format it on my pc, to use in a Raspberry Pi, suddenly it only showed half of its storage capacity! No explanation for it, and no suggestions online on how to fix it. I would never buy one of these again.

Card failed after a little over a year of use - fortunately able to be read from (so I didn't lose my vacation pictures) but unable to write to the card or format it. Requesting an RMA. It was used in a Surface 3 for about a year and then moved to a camera, but there was very little insert/eject or exposure to harsh elements so such a short lifespan is unacceptable.

Dead and totally unrecoverable within 4 years

I don't expect things to last indefinitely, but 4 years of sitting in a phone reading mp3's and saving the odd picture just isn't good enough. Meh.

If you want flash memory then Samsung is the way to go, in my opinion. Over the years I've just seen too many issues raised with other brands to waste my time and risk my data. Samsung has never failed me.

This is the second Samsung 128GB EVO+ card I've bought and will likely be the last Samsung branded memory card I buy. The first stopped working after 6 months. The second, while lasting a little longer at 1 year and 8 months has just failed also. I guess I'm slightly lucky in the the corruption of the card preserved the contents on it but it can no longer be written to, only read from. Which means you cannot add new files or delete old ones or erase or format the card.

Works ok for two years in my phone, hade no issues for that time, good genuine, not fake item with lower capacity than it says.

It was working good but then all of sudden card stopped working and was showing error when I was moving files from the SD card to my laptop, I lost everything I had on the card, I wouldn't even allow me to even format the card. I would suggest backing up everything on the card on regular basis as it seem like you couldn't rely on this card.

Very fast microsd, I use it to store game data on my samsung tab s2. The games - some of them with high requirements like Game of Thrones, played really well without the slightest bit of lag. The write speed is less great, but usually can transfer 1GB of data in about 50 secs. from the computer. Comes with a handy adapter so you slot the microsd card directly into your PC>

Consiglio a tutti questo ottimo prodotto di casa samsung, funziona perfettamente, sd comprata per essere utilizzata all'interno di una reflex, fa egregiamente il suo dovere. Pagata 33euro durante il black friday. che dire ottimo la consiglierei a tutti

Bought to expand the storage capacity of my phone. It may not be the fastest card you can buy but it seems more than capable of holding lots of photographs and music which I transferred to it via my PC. I believe that it represents good value for money.

I ordered this for my samsung tablet after reading previous reviews, i needed a memory card with a large storage and decided upon this brand. So far so good, it has more capacity than i need at the moment but might need more capacity in the future.

I needed more storage for my Samsung S9 and this was perfect. I paid a little more to guarantee quality and security of my data.

Cards are very good, but after some year/two the data started disappearing from the cards.