See pictures for actual measurements.  Tag says 16, measures like a medium to smaller large.  Vintage, thinking 50's but not sure.
This Vintage Pendleton 100% Wool Flannel in size M features a classic brown plaid pattern, making it a versatile addition to any man's wardrobe. Crafted in the United States by the renowned brand Pendleton Woolen Mills, it boasts a button-front style and long sleeves, perfect for everyday wear. The high-quality wool material ensures both comfort and warmth, while the original design adds a touch of timeless style to any outfit.