The Rime Light is a hybrid jacket made with two different materials. Most of the front and back made with a soft and lightweight material that is PFC-free DWR treatment. This makes most of the jacket both wind and water repellent. These sections of the jacket are insulated with Mammut’s LOOPINSULATION, that provides a very decent ratio of warmth to weight ratio. This was really demonstrated by keeping my core warm while running in -25 C conditions. 
  Where the high level of breath-ability comes from is the lightweight and highly flexible panels in the arms and sides of the body. An area that is usually sheltered from the elements anyway, but allows for moisture to escape from the base and mid-layers.

Some of the additional features are:

• The hood is a close fitting that can easily be warn under a helmet.
• One Zippered inner pocket and two outer pockets that will not interfere with back packs nor climbing harnesses.
• It is an ‘athletic’ fit which means it will fit closely to your body. I did not have any problem fitting both a mid and base layer underneath it.
• The sleeves are a good length and have nice elastic cuff that you can fit gloves either over or under.

It has a very small packing volume. Mammut says it can fit in the front right pocket, but I had to do some serious stuffing to get it to pack down. However, one of the advantages of the polyester based LOOPINSULATION is that it springs back nicely. A nice touch is that the right-hand pocket has a grey zipper pull tab to identify which pocket to stuff the jacket into.

• Filling: 100% Polyester
• Insert: 89% Polyester, 11% Spandex
• Lining: 100% Polyamide
• Main material: 100% Polyamide

• Hybrid construction with stretch sections for additional freedom of movement and temperature regulation
• Extremely soft, lightweight, wind- and water-repellent material with a PFC-free DWR treatment
• Mammut LOOPINSULATION (40g/m²)
• Lightweight, highly elastic Polartec® Power Grid® fleece with high breathability, excellent moisture management and short drying time
• Fitted hood can be worn under a helmet
• 2 backpack and climbing-harness-compatible zipper pockets
• Zippered inner pocket
• Elastic hem and cuffs for improved fit
• Small packing volume: Jacket can be stowed in the front right pocket

This jacket pleasantly surprised me under such cold conditions and without a shell. I really like that this Jacket works both as a mid-layer and as an outer layer. In addition to the above run, I also wore it on a short ski tour as a mid-layer. When I got to the top, I was expecting to swap it out for a heavier down jacket that I had in my pack, but I ended up just continuing with just the Mammut Rime Light. The body mapping and my base layer did a great job of wicking moisture away from my skin.

Mammut promotes this delivering warmth and comfort for a wide range of mountain sports… I would take it a step further and that it also delivers warmth and comfort under a wide range of mountain weather. I would not hesitate to wear this jacket from early fall, through the winter until late spring. I will even throw it in my pack during the summer for those freak Eastern Rocky Mountain summer snowstorms or cold nights.