Has been repaired - sewn in the shoulders.

WWII U.S. Military wool-blend thermal undershirt.
This specific design was standard issue for the U.S. Army and Navy during the 1940s to provide insulation in extreme cold weather. It features several highly distinct details that confirm its authenticity:
The Silhouette: It has an exaggerated long length (designed to be tucked deeply into trousers so it wouldn't ride up during movement) and a narrow, highly elastic body.Knit Structure: It utilizes a distinct heavy ribbed knit construction (rather than the waffle knit patterns that became much more dominant in post-war eras).
Construction: It features heavy-duty flatlock contrast stitching along the shoulders and arm seams, designed to prevent chafing under field uniforms.Color: The fabric is in the classic Olive Drab / Khaki (OD-3) shade typical of early-to-mid 1940s U.S. GI issue garments.