The linen tunic: there's just nothing better.
Start with the fabric. It's all linen, all the time – which means it always feels super cool and comfy. The tunic length means this is a shirt you absolutely want to wear untucked (breezier that way). But the pièce de résistance may be the sleeves. They're long – but have nifty button tabs so you can roll and secure them on warm days. All of which lends itself to the casual "It's my day off and here's what I'm doing with it" vibe.