Vintage Fox Knapp flannel shirt size medium 1960s rare

Vintage Fox Knapp flannel shirt size medium 15. Heavy wool. Heavy like a jacket but not a jacket. Vintage. Seems to run a bit small for a medium. Check measurements. Awesome plaid pattern in blue, green and brown. All buttons work. No flaws that I can find. No holes. No stains. Excellent condition. Corner of one of the front pockets curls a little but could probably be remedied. I haven’t tried. True vintage 60s. Rare. Measurements while laying flat: Pit to pit 20” Top of shoulder to very bottom 26” Top shoulder seam to end of arm 22” Collar to end of arm 29”