The Mountain Equipment Frostline Down Jacket offers an impressive warmth-to-weight ratio, making it ideal for mountain activities. Key features include a weather-resistant shell, 700-fill power-down insulation, an adjustable hood, multiple pockets, and packability.Mountain Equipment says:An ultralight duvet with a weather-resistant shell for alpinists and trekkers needing extra warmth and a tiny pack size.A minimalist, low bulk down jacket that provides essential extra insulation on fast moving days. DRILITE LOFT shell fabric gives impressive weather resistance for added peace of mind in exposed situations and a protective hood extends the Frostlines range further still.Our VerdictThe Mountain Equipment Frostline Down Jacket is a lightweight yet robust insulation layer for alpinists and trekkers. It offers an impressive warmth-to-weight ratio at just 353g (UK12), making it ideal for fast-moving mountain activities.Key features include a weather-resistant DRILITE LOFT shell, which provides wind and water protection without compromising breathability. The 700-fill power-down insulation offers excellent warmth for its weight.The jacket’s versatility shines through its adjustable hood, multiple pockets, and the ability to pack into its pocket for easy storage. The two-way YKK front zip adds convenience for harness compatibility.The use of 100% recycled materials for outer and inner fabrics is particularly noteworthy, appealing to environmentally conscious users. The FC-free DWR treatment further enhances its eco-credentials.While the stitched-through construction may not be as warm as box-wall designs in extreme conditions, it contributes to the jacket’s low bulk and packability.- Reviewed by Ultralight Outdoor GearFeaturesStitched-through baffle construction throughoutAdjustable Elastane bound Mountain HC Hood2-way YKK moulded centre front zip2 zipped hand warmer pocketsNapoleon chest pocketElastane bound cuffs and adjustable dual tether hem drawcordsPacks into hand pocket with twin karabiner carry loopsSpecificationsXSmall (UK 08) weighs: 321gSmall (UK 10) weighs: 336gMedium (UK 12) weighs: 353gLarge (UK 14) weighs: 379gMaterial & Construction100% recycled DRILITE LOFT 20D outer fabric with FC free DWR; totally windproof and highly water resistant108g (Size 12) of Pure Down with a minimum content of 90/10 700 fill powerFabric: 20D x 20D 40DContent: 100% Recycled Polyamide outer; 100% Recycled Polyamide inner; Down fillHelp & advice:Choosing a Down JacketDown QualityAll About DownHydrophobic Down

The Mountain Equipment Frostline Down Jacket offers an impressive warmth-to-weight ratio, making it ideal for mountain activities. Key features include a weather-resistant shell, 700-fill power-down insulation, an adjust