Castelli believes so much in the power of fabric which is used to make the sleeveless base layer Core Mesh 3 which moved away from the usual name of the fabric associated with the characteristics and called it Magic Mesh. Before you get skeptical about the fabric's otherworldly name , please note that when creating the mesh, the brand removed all traces of less breathable Lycra using only the most breathable polyester fibers to provide maximum moisture management. Place this lightweight layer under a summer tank , you will actually speed up the process of evaporation of moisture from your skin helping you stay cooler and drier as you move through hot, humid air.