I wear the shirt under it and, after the first cycle and the first wearing only praise. I wear T-shirts with shirt and polo for many years, have a wide variety of experiences * grrrr * done - now I'll stay guaranteed at it and order meeeehr it because: Good fit (good elastic with 7% elastane content) have the basis of other reviews rather "L" instead of "XL" ordered (182cm 85 kg) and fits. Punctual delivery and very fast despite Ösi address ;-) and therefore absolute recommendation !!!!