The castelli velo jacket the castelli velo jacket was sewn from forcefield fabric this extremely lightweight fabric is a 30 gram ripstop material that is windproof and water resistant it39s so light in fact that you39ll barely notice it against your skin additionally it is highly breathable so that when you are working up a sweat you won39t get drenched from the inside out the velo jacket features covered ventilation ports on the sleeves and the back to help exhaust heat away f