I don't have the capability to measure my head at the moment, but I've had several other people try the liner on, and so far no adult man has been able to fit it on their head (this was after doing several things to try and increase the diameter of the liner). At this point I'm thinking the liner is likely defective, but I want to be sure before I go about trying to get my money back. Does anybody have something I can compare my measurements to? Thank you

Each unit that was created for and during Vietnam has a distinctive patch with its own pattern. A reoccurring theme with Vietnam era military patches, especially for the Army and multi-service units listed above, is a vertical sword in the center of the patch. The Signal Corps’ tell-tale sign is the presence of a lightning bolt somewhere on the patch. The lightning bolt represents the radio signals sent out by their equipment.   https://www.medalsofamerica.com/blog/vietnam-military-patches/    

I agree. Not a fan. 

'CMAV'- Military Assistance Command Vietnam....LLD #4- Literacy & Language Development #4 (?)....Perhaps language training for RVN troops on the use of military communications equipment?....Bodes

Just the direct opposite the WWII KIT is far more difficult to find thus more expensive.   R.E.

Holy crap! That’s an Awsome find! Did you find it in Irvine? And where?

400-800 would be my guesstimate. Cool find, good for displays or you war room!

I mean its possible but doesn't it resemble any badge I have seen from them. I was told that it could be a Ww1 Pioneer Infantry regiment but I am not sure. Also their symbol isn't 2 axes. It 1 axe and one 1 mallet.

Woodsmen of the World (WOW) badge?

Now thats both true and funny.