The SanDisk Ultra 80MB/s is a new card that replaces the Ultra 40MB/s. The 80MB/s is the read speed only. SanDisk refers to the write speed as Class 10, which means the card maintains at least 10MB/s continuous write, but does not state a maximum write speed. I tested the following Ultra 80MB/s cards: (2) 32GB, 64GB and 128GB and compare with the previous Ultra 40MB/s cards. I use CrystalDiskMark benchmark (5 passes, 1GB random data) and USB 3.0 card reader.SanDisk Ultra 80MB/s (new version, September 2015) 32GB (1) Read: 94.2 MB/s Write: 43.0 MB/s 32GB (2) Read: 97.7 MB/s Write: 20.9 MB/s 64GB Read: 82.4 MB/s Write: 19.1 MB/s128GB Read: 97.7 MB/s Write: 38.5 MB/sSanDisk Ultra 40MB/s (old version, 2014-2015)32GB Read: 47.8 MB/s Write: 19.9 MB/s64GB Read: 47.8 MB/s Write: 16.2 MB/sREAD Speed: Ultra 80MB/s cards exceed 80MB/s read speed and are much faster than the old version. This allows fast downloads from the card to your computer when used with a USB 3.0 card reader. Using USB 2.0 it limits the speed to about 35MB/s.WRITE Speed: Benchmarks can be deceiving! The benchmarks show a big difference in write speed between cards. One 32GB card measured 43MB/s but one from a different source was 20.9MB/s. When writing actual files the write speed varies during transfer. The 128GB card benchmark was 38.5MB/s write, but transferring a large file I see a range between 16-24MB/s throughout the transfer. Only the faster 32GB card was able to maintain above 40MB/s write speed for the duration. There was also a big difference in 512K random write performance between cards (~1MB/s vs 20-24MB/s).Write speed of 15-20MB/s seems to be typical of Ultra cards. They are good for general photography, but not fast enough for extended continuous shooting. Once you hit the buffer limit in the camera it can become very sluggish if the write speed is not high enough. If you only take one shot at a time the write speed speed should be sufficient.I am tempted to remove a star because of the variance between cards, but all cards exceeded their speed ratings. The improved READ speed over the previous version is a benefit. Actual write speed may not be much better than the older cards. You might get an extra fast sample, but do not buy this card expecting outstanding write performance!