yp221

Looks like he was Army, not Marine Corps.

This website has a very similar patch: http://www.usarmypatches.com/WW1 A-Z.htm Says its Headquarters Armored Units.

Castel del Monte, Italy

1939

Since this has my curiosity, I looked through a few of my references on the Arizona. I was wrong in the above post, couldn't find any life preserver's marked ARIZ. But I did find a few pics of different styles of markings from the early 30s to 1939.. None of which look like the one in the auction. Early 30s

I thought the Arizona's life preserver's were marked simply "ARIZ" (like the ship's boats).

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Class of 1951. KIA in Korea. https://www.west-point.org/users/usma1951/18275/

Looks like the type/style of rivets seen on saddles, saddle bags, rifle scabbards, etc.

Great looking helmet, here's your guy

20th Infantry Regiment. The crossed rifles make the Roman numeral for 20

Is it possibly a two digit number? Maybe it's a number to quickly identify your equipment amid lots of identical gear in the arms room or barracks. Either way it's pretty interesting.

ZC60. Its fine.

Nice helmet, looks like it's been posted here before: http://www.usmilitariaforum.com/forums/index.php?/topic/221497-us-navy-m-1-helmet-opinions-please/?hl=langley The liner chinstrap looks like a European copy, but still a nice honest helmet

103rd Infantry Regiment