Lowe Alpine have produced an absolute winner with the Frozen Sun Jacket, it uses the perfect blend of Polartec Alpha synthetic insulation & technical fabrics to produce a superb winter mountaineering jacket. The highly breathable nature of the filling makes this jacket more suitable for active users in demanding conditions, if you are looking for static warmth we would recommend a down or Primaloft filled jacket. Polartec Alpha is a woven insulation fabric; think of it like a fluffy string vest, & is much more stable & durable than other synthetic insulation. Because of its more open weave it allows air to flow much more easily, rapidly drawing moisture away from the body creating comfortable breathable insulation for active use in in cold conditions. Lowe have used two different weights of Alpha to maximise performance & minimise weight; the body uses 100g/m² & the arms use 80g/m². To keep you protected from the elements the Frozen Sun uses a Pertex Microlight Stretch fabric which, as the name suggests, has built in stretch for ease of movement, is very lightweight & has a Durable Water Repellant to resist all but the worst of the weather. Even the mesh lining has built in stretch so this jacket feels superb when you get it on. Should your jacket get soaked the synthetic Alpha insulation & the Pertex fabrics all dry out exceptionally quickly. Featuring a helmet compatible hood with a wired peak, harness compatible hand pockets, a chest pocket & a soft lined collar for enhanced comfort. We reckon this is the best example of any Alpha insulated jacket & really makes use of the insulations amazing properties. Pertex Microlight stretch outer Polartec Alpha insulation 100g/m 2 / 80g/m 2 Stretch wicking mesh lining Helmet compatible hood with wired peak 2-way YKK front zip with internal storm flap & lightweight sliders Tricot-lined collar 2 x YKK zipped A-line pockets 1 x YKK zipped chest pocket Adjustable hook & loop cuffs with stretch gusset Adjustable hem drawcord