It's the Mutambo Camp Shirt. Small logo on the front, big on the back.

• 100% cotton
• Sport Grey is 90% cotton, 10% polyester
• Ash Grey is 99% cotton, 1% polyester
• Heather colors are 50% cotton, 50% polyester
• Fabric weight: 5.0–5.3 oz/yd² (170-180 g/m²)
• Open-end yarn
• Tubular fabric
• Taped neck and shoulders
• Double seam at sleeves and bottom hem