Much like the Polaris Vortex, this is another item classed as a jacket that really is more of a heavy winter jersey.
The N2S system is supposed to be worn next to your skin, without a base layer, although we would suggest a thin vest layer for those susceptible to nipple rash. If you're not the type who chaffs up easily then this is one of the best bits of winter kit you can buy. We've got four year old examples of this N2S top that have been hammered, washed wrong, and generally abused, and they still work.
There is a single zipped pocket at the rear large enough to store the removable sleeves and lots more. There's plenty of reflective piping and the cut is amongst the best available, similar to the fit of the Rapha (left) in many ways. Aside from being incredibly windproof thanks to the Windstopper membrane, it is also showerproof and will stay that way through a good few years of washing.