Delta changed from the horizontal format for the fourth set of cards. As well as changing the cards to a portrait format, they added a holographic image that changed depending on the direction it was viewed. The secondary image was the same on all cards, but the aircraft image changed with the card. Delta also moved the card number to the front of the card for the first time.

These cards are very difficult to image due to the shifting picture. Also, most of the pictures of the aircraft are only a part of the aircraft, so it can be difficult to figure out what you are looking at.

See more information on all Delta Pilot Cards on https://deltapilotcards.com/