Suggested SD Card Size

[fzinken]

Please don’t ask questions twice.
Your question has been answered in

USB Stick Recommendation for OSMC on ATV?

The ATV1 has USB 2.0 Support. That said, you may want to get a stick that supports USB 3.0 since it will be more useful later, and the nand flash might be better quality/faster. As long as the stick if fully USB 2.0 compatible, has fast random access, and IS NOT a U3 Type, you should be good to go.