- Men's storm 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® Linen shirts have the power to take the edge off formal looks. With its Mao collar and storm-blue coloring, it goes just as well with jeans as with Bermuda shorts.