The Mar Cotton Linen Shirt in Mocha from Knickerbocker, NYC. 

Details
The Mar Shirt Blends The Design Of A Classic Mechanic's Work Shirt With High-Quality Cotton And Linen Fabric, Accented By Mother-Of-Pearl Buttons. It Features Two Large Chest Pockets, Vented Side Seams, And A Double Back Yoke Detail.

• 55% cotton, 45% linen, woven in Portugal
• Mother-of-pearl buttons
• Made in Portugal