Santini Mesh Cycling Base Layer Vest This sleeveless base layer shirt features a seamless design with polypropylene anallergic yarn. It reflects thermo energy generated by the body back into skin tissues as far infrared rays to enhance performance and recovery. This lightweight, breathable base layer offers superb comfort and fits like a second skin. Features Include:- Seamless design Polypropylene anallergic yarn Turns body heat into energy Fits like a second skin