Compatibility

Basically used, that has not been upgraded to watchOS 6, or ild unsold inventory.

If getting used make sure the seller has followed these instructions

https://support.apple.com/en-us/HT208855

otherwise, you will not be able to use it.

Or wait until you get a newer iPhone 6s, SE (1 or 2), 7, or newer.

Any watch that has watchOS5 or lower.