For good performances we recommend:

SD card:
DELKIN Black UHS-I 90 MB/S cards
https://www.delkindevices.com/delkin-black/

Sandsik Extreme Pro SDHC/SDXC UHS-I (95MB/s), today you will find 32GB/64GB sizes.

USB Thumb drive:
SanDisk Extreme USB 3.1 Flash Drive (128 GB/ 256 GB)
Sandisk link: www.sandisk.com/home/usb-flash/extremepro-usb

Please note, fat32 will be used in all cases.
Be careful to order to a trusted dealer.

Notes:

• Even if the Sandisk SDHC/SDXC UHS-II (280MB/s) are compatible with the Cantar X3, they won't be faster than UHS-I.
• Even if the speed is slower, the Sandisk Extreme PLUS SDHC UHS-I and the Sandisk Extreme SDHC UHS-I have been tested.
• The other SD/USB manufactured can also be used, but haven't been tested.
• If a media stay RED (>100%) during the record, it is too slow for the current configuration.
  In such a situation, the solution is to switch the RED media in idle mode (backup in background), to get back to a safe behaviour.