Described by Castelli as “our most innovative jacket ever”, the Alpha will keep you warm in all but the most extreme conditions, even when worn over just a base layer. Our favourite thing about the design of the Alpha is its dual layer construction, which enables you to open the windproof layer independently from the insulating layer. In practise, this means that it is much easier to effectively get cool air where you need it, preventing overheating and unwanted moisture buildup (which can then later make you too cold when you do cool off or stop).
Our second favourite thing about the Alpha (there are quite a few things about this jacket which we really like!) is its use of advanced patterning on the fabric, which means that the jacket fits close to the body but will also work with a range of body shapes. The Windstopper fabric is very lightweight and breathable and will block wind effectively, as well as providing some water resistance. The jacket is finished really well, with raw edge waist and cuffs for a smooth, flexible fit and good glove interface. The asymmetric zip is easy to use and doesn’t bunch. The articulated collar effectively keeps out draughts and sits comfortably against the neck and the jacket is finished with reflective details for that added peace of mind when light levels drop.