Castelli Cold Days 2nd Layer Polartec Alpha Long Sleeve Warmer - AW26

Added insulation, extended warmth.

The Polartec® Alpha® fabric is an amazing insulator, and it’s soft, stretchy, and lightweight. 

A couple of years ago Castelli thought it would make an excellent fabric for a base layer, but it tended to feel wet and clammy against the skin. But when looking for more insulation for sub-freezing gravel rides, Castelli tried using the Alpha® prototypes as a second layer on top of a Prosecco base layer — and stumbled into the best combination for cold-weather riding. 

Castelli worked on the details and created this second layer for cold rides. They've given it a half zip so it doesn’t create bulk over the lower torso, and mounted the zip slightly off-center to avoid the bulk of multiple zippers at the neck. Castelli kept the fit close to body, so you have the choice to tuck it into your tights or leave it out like we do. They also found that it works well over a Flanders, Bandito, Miracolo, or Seamless base layer.

Features

• Polartec® Alpha® 90 high-loft active insulation fabric made from recycled PET
• Maximum breathability
• Asymmetrical zip
• High collar