SanDisk Ultra SDXC Memory Card 64GB Class 10 UHS-I with a read speed of up to 40MB / s (064G-SDSDUN-FFP) (Accessory)
The card is announced for the 40 MB / s. Obviously Sandisk forget to indicate whether this is valid for both reading and writing. Moreover, in the Amazon reference is specified UHS-I, or anywhere on SD is marked (no logo I in a U, below the SDXC logo