12x20 gable shed build

[RC20]

Hi, have a question regarding the video where a 12x16 gable shed is being built. It looks like they were installing some sort of metal strip in between the the top of the full sheets of siding and the pieces at the top of the end walls. I don’t see that anywhere in the instructions. Can anyone explain what they used and why? I’m at that point in my construction of the side walls and don’t want to move forward until I understand that better.
Thank you

 

[Paisley]

I might be how better if you share in the video and the time stamp. However, my first impression is to guess it was a drip edge of some kind