GPM stands for Gran Premio delle Montagne, or Italian King of the Mountains. Though not the absolute lightest, the Castelli GPM Sleeveless Jersey FZ is the most comfortable sleeveless cycling jersey to ever reach the summit. The sleeveless arm openings and collar are seamless, so there are no stitches to irritate your neck and arm pits. The full zipper allows for maximum ventilation. A classic, in four rich, solid colors.

• Stratus fabric with Prosecco treatment
• Seamless, microfiber collar and arm bands
• Full length locking zipper
• 3 back pockets and zippered key pocket
• Reflective tabs on back