Castelli Core Mesh 3 Base Layer WhiteThe Castelli Core Mesh 3 base layer is designed for the hottest cycling routes, as it absorbs and expels sweat and promotes maximum air flow so you can maintain optimal body temperature and perform better for longer. Castelli Core Mesh 3 Base Layer WhiteThe Castelli Core Mesh 3 base layer is designed for the hottest cycling routes, as it absorbs and expels sweat and promotes maximum air flow so you can maintain optimal body temperature and perform better for longer.