Least expensive reliable SD cards for sustained 6k HEVC on S1 In: Cameras Posted August 12 If it helps you decide, I use V30, 90MB/s write, 160MB/s read speed rated SanDisk Extreme 128 GB micro-SDXC cards (in SD adaptors) in my Lumix G9 for 150Mbit 4k50p with no problems. Recently I've paid around £23 for these in the UK. There are also equivalent standard SD card size versions. The (theoretically) better 'Extreme Pro' versions of these (similar performance) can sometimes be bought for not much more if you shop around. V30 rating = 30 Mbyte/s = 240 Mbit/s sustained sequential write speeds, so 200 Mbit/s 6K HEVC is theoretically OK. Personally I've always found the higher grade SanDisk cards to perform well i.e. read and write speeds are at least as good as the spec.