Castelli criterium jersey fz is the warmest thermal jersey on the castelli collection the think and fleecey warmer fabric providesa lot of insulation yet delivers great moisture management with good stretch for a perfect fit we kept clean design lines so itll look goos on its own or under a vest and castelli have added in a big reflective stripe to give extra protection on those shorter fall days warmer fabric is our warmest nonwindproof thermal fabric reflective insert at upper chest and