I recently bought this memory card to test on a UHS compatible camera Canon 6D. This actually has a Read Speed of 60 MB/s (400X) and the maximum Write Speed is only 40MB/s.Sandisk memory cards has been my choice since a few years after using ADATA, Sony and other brands mainly because the data transfer rate remain consistent and true to what's advertised.If you are wondering what UHS is?UHS Speed Class was introduced in 2009 by the SD Association and is designed for SDHC and SDXC memory cards. UHS utilizes a new data bus that will NOT work in non-UHS host devices. If you use a UHS memory card in a non-UHS host, it will default to the standard data bus and use the "Speed Class" rating instead of the "UHS Speed Class" rating. UHS memory cards have a full higher potential of recording real time broadcasts, capturing large-size HD videos and extremely high quality professional HD.The UHS-II interface was first announced in early 2011 and just now are we starting to see both UHS-II memory cards and host devices come to market. These are the professional level SD cards for recording 4K videos and higher.This is for you if:1. You have a recent semi-professional or professional body (Canon 6D, 70D, 700D etc.,) and regularly shoot in RAW2. You are film maker with a professional camera capable of recording Full HD and your camera is UHS compatibleIf you are unfamiliar with SD card varieties (class 4, 6, 10 or UHS), here is a brief description below.There are two kinds of Speed Class basically - Speed Class (class 2, 4, 6, 8 & 10) and the newer UHS Speed Class (Class1 and Class 3). Each class has a minimum write speed.Class Minimum Speed2 2MB/s4 4MB/s6 6MB/s8 8MB/s10 10MB/s____________________________UHS 1 10MB/sUHS 3 30MB/s___________________________UHS-II Stardard 250MB/s (For 4K and 3D Video Recording)What do these numbers mean?1. For Still Photography - This measurement is useful especially for taking pictures with very high resolution and/or saving in RAW format where the files created are very large. The faster the card, the faster it can save the file and be ready to take another picture. You can really notice speed differences with high-megapixel DSLR cameras when using multi-shot burst mode.2. For Recording Videos - The Speed Class - 10 is required for most DSLRs on video mode recording full HD or camcorders, where the device is actually saving a steady stream of data. The resolution and format of the video determines the amount of steady stream data. This translates to a minimum speed you need to guarantee that the video captured on the cards is recorded at an even, sustained rate with no dropped frames (which would result in lost data and choppy playback). Let's say you bought a new camera recently and it's capable of recording Full HD and 2K, then even a class 10 may not be enough. That's when UHS-3 is going to be useful with a minimum write speed of 30MB/s. 4K and 3D Video Recording require UHS-II interface with write speeds more than 250MB/s.FAQ1. I am hobbyist photographer. Are higher-rated cards faster while using it on a DSLR camera?No. Autofocus, turn-on speed, JPEG and movie recording even at 1080, image review, maximum framerate, and so on are almost completely unaffected by faster cards. Movie recording at 1080p/30frames takes just about 10 -15 MB/s on a canon 60D (Not a UHS compatible body)2. I have a Non-UHS compatible body (Canon 60D) but want to use UHS class 3 instead of a regular Class 10. Will it not work?Yes it will work but not to its full potent.Remember that you are spending more money for a feature you can not use on your non-UHS compatible camera. But that being said, the speed is significantly a lot faster while transferring the data to a computer or perhaps you may upgrade your camera to UHS compatible one at some point in the near future, it is definitely worth buying the newer UHS SD cards.In short, if you are planning to become a professional photographer or a film maker eventually, buy it right away as it is worth it.