OK, here's the bottom line on this overshirt joint: it's sick, there's nothing like it, and you should strongly consider adding it to your rotation.
This style, from Wax London's continuing Whiting collection, comes in a heavyweight cotton weave fabric.
It features two patch pockets and Corozo Nut buttons. It's best worn as a relaxed-fit shirt-jacket with a t-shirt!
There you go. You're welcome. It's your new look. Thank me later. --Justin