As more prosumer and professional cameras gain the ability to record 4K, high-speed, or RAW video, we're once again reaching the limits of consumer flash storage. Most professional camera makers have proprietary (and expensive) storage modules for their cameras, but some are also adopting new flash memory standards for secondary storage options. Sony and Lexar have adopted the XQD format, a PCIe based-standard that target speeds of up to 500MB/s (and 1GB/s in the 2.0 spec). Memory card maker SanDisk, however, is skipping XQD in favor of its own CFast 2.0 standard, for which it just launched its first memory card. The SanDisk Extreme Pro CFast 2.0 has a maximum read speed of 400MB/s and max write speed of 350MB/s, making it technically the fastest memory card in production. It's not for your DSLR, though--only ARRI's new Amira camera supports CFast, and XQD is only compatible with a handful of Sony camcorders and Nikon DSLRs. The upshot is that these new memory cards aren't something the vast majority of you will have to be concerned about. But if you're looking to buy an SD card for your camera, don't forget these handy guides!