- Men's horizon blue shirt - Mao collar, long buttoned sleeves - EASY-REGULAR shape, 100% linen - Button closure, IKKS button left cuff - IKKS #actforbetter: material containing 100% linen certified Masters of Linen® and European Flax® More casual with its Mao collar and 100% linen fabric, the Men shirt is no less stylish. Choose it in pastel blue, to compete with the color of the sky.