With this flash drive, you can either use it to upgrade a system you currently have loaded with data (i.e. from Yosemite up to High Sierra) or you can use it to perform a fresh, clean install of the OS. 

Provided below is the link to Apple's officially supported documentation of High Sierra's minimum hardware specifications:

https://support.apple.com/en-us/111934#:~:text=These%20Mac%20models%20are%20compatible,Air%20(Late%202010%20or%20newer)

The format of the flash drive is USB Type-A and the size of it is 16GB

I do offer faster shipping options than USPS Ground Advantage, but they do require you to pay a shipping fee. If you purchase one of these options, my handling time will be either same-day as the order, or next day, just depends on when the order is placed.

Please reach out to me if you have any further questions regarding this listing. I want you to walk away from this transaction happy and with your equipment in good, working condition.