Originally Posted by xliioper

The full terms and conditions can be found at the bottom of the following webpage (you will need to expand the terms section) -- https://www.delta.com/us/en/booking-...n-certificates

Reserve certs are good for US48 tickets in main cabin, C+, and First Class (but not Delta One), but there must fare availability for both pax in L/U/T/X/V classes for main cabin/C+, and I/Z for First Class. There may be additional inventory limits beyond fare class, but they don't specifically have blackout dates. Just as with other tickets, your companion (who must be on the same reservation as you), will be upgraded along with you at your priority level. Although you should check-in in the same transaction if you want insure you are upgraded at same time after check-in.