INSULATION
Synthetic insulation is durable and will keep the user warm even when it's wet. It is cheaper, bulkier and heavier than down, but modern synthetic fills are coming close to matching down in weight and compressibility. Down offers incredible warmth to weight and will most likely be treated with a hydrophobic coating that will resist soaking and enable it to dry more quickly. This means that in wet conditions, down won't ‘clump’ so easily whilst still offering warmth.
BAFFLES
Down jackets use baffles to keep the fill from moving around. Some synthetic garments also use baffles amongst other techniques. Seamless (welded or seam-sealed) construction reduces heat loss through the stitching.
Articulation
Jackets are cut to ensure warm air remains close to the body,
