Best Memory Card Sony RX1R II | Real Benchmarks
The RX1R II needs a U1 speed class card or better for 1080p video recording. Video writes data at 50Mbps, which is 6.25MB/s.
The RX1R II can use memory cards up to 128GB. You can use 64-128GB cards without any problems. The RX1R II cannot write faster than 36MB/s, so you do not need to buy the most expensive cards.