from GLouie, 3 cycles filling up the card, total test time: 8.5 hrs:
MixPre10II firmware 7.11
32b float-192kHz
recorded 8 ISOs
3 passes until disk full message, no error messages
Sandisk Extreme 64GB SDXC - UHS-1
Model SDSDXV6-064G-GNCIN
150MB/s
serial#BN19274835730
Made in Taiwan
Black Magic Designs Disk Speed Test v3.3
2017 iMac, built-in card reader
Write: varies, around 58MB/s
Read: varies, around 90MB/s
Vendor unknown, these were a gift, but I gave the B&H link. Curiously, out of 3 cards, 2 were made in Taiwan and 1 was Malaysia.
This card is on the Sound Devices tested media list of Jan. 15, 2021.