What was the chest buckle on some B3 repros?

[MattieXMoto]

I have seen mostly on the arctic B3. Like this one by RMC. What was the functionality of that buckle near the chest?

The only thing I could find was below. See pilot #4. One of his collar straps are buckled into that chest buckle. Not sure why and if so, why kot angle the buckle to accept that collar strap easier?

Camp Skeel Mich, december 1940

Hello, I tought it might have some interest for prewar jacket lovers. This picture has been taken on the 12th december 1940 and is noted on the back "army air corps pilots making aerial combat studies at Camp Skeel, Mich., returning to their barracks after a test flight". I like the different...

www.vintageleatherjackets.org

 

[ABCD]

Not sure why and if so, why kot angle the buckle to accept that collar strap easier?

Attaching the lower strap to the lower buckle and the upper strap to the chest buckle still keeps the collar up right but increases its size sufficiently for a USAAC pre-War oxygen mask to be accommodated.

By the way, there's a thread for questions like this.

https://www.thefedoralounge.com/threads/ask-a-question-get-an-answer-about-outerwear.102916/