Based off of comparisons of the knitting, stitching, and buttons to other confirmed pieces, I believe this is a World War Two era example of the high neck sweater that was issued to United States military members. Unfortunately the label is gone and the only marking is a stamp of a number at the collar, which I was unable to find the meaning of. Items has many small holes as shown, which is common for wool pieces of this age, as well as some pilling at the armpits. Original size unknown, see measurements in photos.