Castelli Size Chart The Promessa Jersey cleverly disguises extreme performance with design details that make people think you bought the jersey for the looks, not the tech. The engineered knit fabric makes the front extra stretchy, while the back has limited stretch so that the pockets don't sag when you load them up. Castelli knit in extra ventilation and subtle design details to balance technical features and sophisticated design. Features: - Engineered knit in polyester/Lycra(R) for excellent fit and moisture management - Limited-stretch back supports pockets even when fully loaded - Full-length YKK(R) Vislon(R) zipper - 3 rear pockets plus zippered key pocket with reflective tape - 18deg-30degC / 64deg-86degF - Weight: 109g