The Castelli Alpha Ros is a lightweight and warm long sleeved jersey. The Alpha Ros has been given a thorough technical upgrade for this year. It has been fitted with the RoS technology, which is shorthand for Rain-or-Shine. This label is only awarded to the most technologically advanced products in the Castelli range, which excel in both dry and wet conditions. Dry conditions demand a comfortable and breathable product, which is capable of quickly moving sweat away from your skin. The rain requires a jersey which can keep you warm and dry. The Alpha RoS jacket combines both of these requirements into a single product.
The materials on both the front and rear are completely new, marking a tremendous step forwards in the field of rain protection. Only the most essential points of the jacket use taped-off seams. Castelli refers to this as "Functional Waterproofing". They can't ensure that not a single drop of rain will find its way in of course. What they can promise you is that, with the Alpha RoS, Castelli has developed a jersey to keep you warm and dry in various conditions.