Vtg German Military Jacket Karl Clavey Rinteln German Flag Green Brown 1960's

Pre-loved men's Vtg German Military Karl Clavey Rinteln Jacket Size 4 on tag--believe this is German sizing--see approximate measurements--best guess on US size would be a medium? Heathered/marled shades of brown and olive drab green German Flag upper area of each sleeve Vintage 1960's USI4a/01/15647/0001/8 2/69 166/100 8405-12-130-5714 No fabric/care tag Shows light wear--see pictures for examples Has storage smell May have wrinkles from hanging in the closet Measures approximately when laid flat: 21 1/2" across front chest, 18" from shoulder seam to shoulder seam, 23" from shoulder seam to end of sleeve, & 27 1/2" from back seam of collar to end of jacket