SanDisk Ultra 128 GB – Tarjeta Micro SDHC con adaptador SD, 80 MB/s, UHSI, Clase 10, por 37 euros SanDisk Ultra 400 GB – MicroSD con velocidad de lectura hasta 100 MB/s, Clase 10, U1 y A1Secure Digital, officially abbreviated as SD, is a proprietary nonvolatile memory card format developed by the SD Association (SDA) for use in portable devices The standard was introduced in August 1999 by joint efforts between SanDisk , Panasonic (Matsushita) and Toshiba as an improvement over MultiMediaCards (MMCs) , 1 and has become the In simple terms, UHS1 Class 1 has a min write speed of 10MB/s, and Class 3 has a min write speed of 30MB/s, and we're talking also here about increased sustained write speed This is a significant difference, and especially critical when recording large amounts of data rapidly, as would be the case recording 4K video U3 Vs U1 Sd Cards A Detailed Comparison Samsung micro sd card u1 vs u3