The Mountain Equipment Paiyu Women's Jacket in Majolica/Stellar is a high-loft down jacket made for serious cold, like skiing for several days or climbing peaks that are 5,000 to 6,000 metres high. It's also light enough to be used in very cold weather.
Heat and insulation
Uses about 269 grammes of 90/10 duck down (size 12) with 700 fill power, which gives a lot of loft and warmth for the weight.
The dual-layer offset baffle construction and heat-reflective inner fabric get rid of cold spots and make the jacket more thermally efficient than standard stitch-through jackets.
It was meant to be a proper "belay/duvet" style piece for standing around in the cold for a long time, not just a light mid-layer.
Shell, protection from the weather, and materials
The shell is DRILITE Loft 40D with a PU coating that keeps out wind and water very well. This makes it good for spindrift, snow, and light rain. The inner lining is made of 20D down-proof nylon that feels good, packs down easily, and helps keep moisture from the layers below. Mountain Equipment's DOWN CODEX can be used to trace down, and it meets RDS 3.0 animal welfare standards.
Fit, hood, and features
Cut to fit over other mountain layers, so it's roomy but easy to move around in. It's meant to be used as an outer insulation layer in cold weather. The Mountain HC insulated hood fits over a helmet, can be adjusted to fit anyone, and is made to protect you well in high winds. It has few seams on the outside to keep water out.
Features: two zipped handwarmer pockets, two chest pockets, one inner zipped security pocket, and two large internal mesh pockets for gloves and water bottles. It also has a two-way YKK front zip, adjustable cuffs, and two hem drawcords. It comes with a lightweight stuff sack.
Best for: climbing in the winter, going on expeditions, ski touring, and using it when it's very cold and you're not moving quickly (like when you're belaying or camping in the UK in the winter).