The Heavyweight Overshirt works great as a shirt, as an easy light jacket, or as a warm mid-layer under a coat. Plus, the 8 oz heavy cotton twill is durable, warm, and twice as heavy as our Japanese Oxford cloth. Overshirt, over-sweater, under-jacket—your call. (It may look like a flannel shirt in the product photos, but click to zoom in on that heavy twill texture.)