Castelli calls this a light jacket but the comfort range is surprising. It dips well into temperatures where you might normally reach for a full protection jacket, yet the surprising breathability makes it still comfortable in temps when you may have worn arm warmers and a vest in the past. And it keeps you dry.

RoS stands for Rain or Shine. It’s a label given to Castelli's most advanced products that excel in both dry and wet conditions. For dry conditions, you’re looking for comfort along with breathability to prevent you from getting wet and chilled from the inside. But with wet-weather clothing, you’re looking for protection that will help you stay warm by keeping the rain out and letting sweat escape.

The Alpha RoS Light Jacket ticks both of those boxes. Both the front and back materials represent a significant step forward in rain protection. These fabrics are used with reduced seaming, and seam sealing where necessary.

Castelli calls this functional waterproofing because while they don’t guarantee that no drop will ever enter the jacket, they promise you that this is their best effort to keep you warm and dry in the widest range of conditions.

Lightweight double-layer wind jersey with significant rain protection
Windstopper® 150 front and sleeves
Nano Flex Xtra Dry back for the most significant nonmembrane water protection available
ProSecco Strada inner liner with 2nd front zip
Waterproof YKK® Vislon® zipper
Articulated collar that fits better whether you’re standing or riding
Front zippered pocket
3 rear pockets with reflective laser-cut drain holes
Raw-edge waist lies flat and moves with you
Advanced patterning makes for excellent close-to-body fit
8°-15°C / 46°-59°F
Weight:340g