IdealasUnder suits or Alone for Good Sun Protection. Madewithmaterial that provides UV protection of 50 . The seams, sewn with flatlock stitching, won't leave marks on the skin. Perfect to wear underneath your suit and ideal for all kinds of watersports. These shirts are a great first layer under wetsuits or a great stand alone shirt for the beach, lake or pool. If you want a loose fit, order a size up. Excellent for wearing under your wetsuits or stand alone. Under your wetsuit, it helps you get your suit on because the lyra glides.