Rab have used their new Cirrus insulation for the Altus Jacket; Cirrus is a 3M Featherless synthetic insulation that provides a high performance alternative to natural down. It was designed to mimic the look and feel of natural down with all the benefits and none of the drawbacks. It retains two times the loft of down when wet, breathes superbly, has no allergens, retains warmth even when wet (more so than Hydrophobic down), compresses easily and dries exceptionally quickly.
 
Rab have used this amazing new insulation in the Altus jacket, so called as it's like having a little cloud of warmth around you, and produced a lightweight synthetic insulated jacket with the equivalent warmth to weight ratio of 600 fill power down insulation. Mini stitch through baffles keep the insulation in place and give the Altus a clean and minimalist look. If you are familiar with Rab products this is like a synthetic filled version of their superb Microlight  Jacket. The filling compresses well when packed and is robust and durable. Its resistance to moisture, warmth when wet and speed of drying are extremely high; superior even to Hydrophobic down and previous synthetic insulation.
 
Pertex Quantum fabric is used for the shell, this incredibly lightweight fabric keeps the filling under control, is windproof and highly breathable and an air-permeable nylon lining is used to optimise breathability. The combination of insulation and fabrics provide unparalleled levels of breathability making the Altus perfect for active use in cold and damp conditions as a mid layer or stand alone jacket. 
 
You get high quality YKK zips throughout and there is a neat zipped internal pocket to keep your phone nice and safe. Lycra bound hem and cuffs keep out the drafts and retain the minimalist theme. When not required the Altus will pack into its own pocket and stash almost unnoticed into your pack making it perfect jacket for all winter mountain activities.