This looks to have been only lightly worn. And it may well be vintage - there hasn't been a Marshall Field's store since 2006.

Light brown, slightly tweedy but I don't know that I would call it a proper tweed, with a very subtle windowpane pattern. Notch lapel, two-button front with 4 on each sleeve, single vented in back. The usual three front pockets, with three on the inside, fully lined, with moderate shoulder padding. This may have once been part of a suit, but I think it works just fine as a sport coat.

I'll be listing several 44L items, and would be happy to combine shipping and save you some money.

Measurements, laid flat and not stretched:

Shoulders (between tops of shoulder seams) 19.25 inches
Chest (pit to pit) 23 inches
Midsection (slightly below top button) 22 inches
Hip width (about 6 inches below bottom button) 23 inches
Center back length (from base of collar in back, to bottom) 33 inches
Sleeve length (along top, from shoulder seam) 26.75 inches
Sleeve bicep width (about 1 inch below armpit) 8.5 inches
Sleeve opening 6 inches

Material: 95% wool, 5% cashmere, unknown lining

Let me know if you have any questions!