Thinking back to my Army days when we had to learn flag sizes, my guess is that’s a garrison sized flag, which is the largest. They were questions in the oral exam for promotion.
Another question was what are the two types of trucks on post? Answer? Wheeled trucks and the ball on top of a flag pole.
Wonder how many know about the truck on the flagpole? It was on the promotional board back in my Army days. Wonder if it still is?