Like Assos’s Fugu jacket, the Castelli Radiation is designed for the coldest winter conditions.
But unlike others it has three layers and various parts that can be unzipped. As always, fit is an important starting point and Castelli has wisely opted for a long sleeve, but a medium that fits six footers is just silly, so check the sizing.
The zip-off hood of the Castelli Radiation works well enough but has to be tight, and frankly a regular fleece hat is more comfortable. The zip-off sleeves are great, and once they’re removed the jacket becomes a heavyweight gilet. As for the silver Radiation jacket, I found it didn’t release enough perspiration, and hated the way it felt on bare skin. Others thought it fine, so it’s obviously a very personal choice.
The Windstopper fabric does a great job, and the waterproofing treatment worked perfectly throughout the test period.
Performance-wise, there are numerous reasons to love the Castelli Radiation; it does a good job of justifying its cost because it does so much for your cash. One little patch of ice could wreck it, however, so the price is a little hard to justify.