In short this is a great card and it's speed falls close to it's advertised speeds. ADVERTISED ACTUAL READ: 160 MB/s 149 MB/s (93.13% of advertised speed) WRITE: 90 MB/s 109 MB/s (121.11% of advertised speed) The results above are from the SanDisk Extreme 128 GB card, SDSQXA1-128G-GN6MA bought in Q1 of 2021. Unfortunately, there are MANY fake SanDisk cards on the market everywhere and they can be very problematic if bought and used. I highly suggest you test ANY sd card that you buy. In general, I always want to get at least 90% of claimed speeds. Different hardware or software optimizations can make it to where you may not get speeds as high as claimed, but if you are close to them, close is good enough. Only read on if you are researching SD cards and verification or are just a nerdy person like myself. When looking up SD cards it's important to keep a few things in mind: * Investigate the claims for speed if it is important to you. The card may say xxx MB/s write speed* That asterisk may reference that the speed is only guaranteed when using a certain software. Since you might be like me and installing the card into a phone, that phone will most likely not use that software so the speeds will be lower. For a more real-world speed, look at reviews who have verified the speeds either in the device that you plan to use it in, or by other software to benchmark it. * Always test the speed of the card once you get it (The speeds above come from a program known as H2testw) * Always test the storage capacity of the card. * I highly recommend that you test your card using H2testw. It tests the two most important things about your storage: actual speeds, and actual storage. Fake or faulty cards cannot hit their advertised speeds. Fake cards often are edited to report a false storage to your computer. Say you buy a 128GB card and you read the size in Windows, 119 GB. Seems close enough right? Well this is not a guarantee of the real storage capacity. The card could be a 4 GB card that is written to report itself as 119 GB. For the first 4 GB of space or so there will be no issues with the card, aside from likely slow speeds, since fake cards often use slower, cheaper memory. After writing these 4 gigabytes however, you will inevitably have data corruption. The original 4 GB stored on the card will start to be overwritten by the next data to come. This can result in a total loss of date. This is the big danger with fake cards. It's one thing to have a slow card, but another thing entirely to lose your data. You could lose valuable data and there are times when this data cannot be recovered. * Know that your storage space will always be less than advertised. In my case, my 128 GB card has an actual storage space of 119 GB. This is in mainly due to the fact that the advertised capacity is often the unformatted, "RAW" size in decimal (base 10) storage. However, your computer reads storage in binary (base 2) storage. In this case, if we take 128 GB of decimal gigabytes and convert it to binary gigabytes, we get 119.21 binary gigabytes. When your card is formatted, it is formatted using base 2 since your computer understands binary. Decimal is essentially only used for advertising as far as us typical consumers are concerned. H2testw will test the true capacity by filling the entire card with however much information it can put into it, then reading it back and verifying that the information stored is correct. A fake card may be 4GB and allow 119GB to be written to it, but when the information is checked, there will be discontinuities in the data and the fake card will be exposed as such. Good luck finding a card that works for you.