Fill power is defined as the degree of expansion of 30 grams of down when subjected to a uniform load. A higher fill power means the down incorporates more air, providing exceptional warmth and performance even in small amounts. UNIQLO down uses 750 fill power or higher.* The result is a product that strikes a balance between everyday comfort and outdoor performance. The density and blend of fill, as well as the fabric, water repellency, and construction, also influence insulation.

Lacking a hard quill shaft, down traps more air for greater warmth. Feathers, by contrast, contain quills that offer better support and flexibility, but with less insulating power. UNIQLO down items use a 90% down, 10% feather fill ratio.* The addition of feathers helps ensure even distribution, creating the ideal balance of warmth, comfort, and lightness.

Down’s sworn enemies are moisture and compression. It's important to maintain its loft through routine care. After wearing, hang your down garment to allow any sweat and moisture to evaporate. You can also check for dampness by placing your hands inside the garment and feeling for cool or compressed areas. During warmer months, avoid storing down in vacuum bags and instead hang it in a well-ventilated space. Most down items can be hand washed. Be sure to hang them to dry on clear, breezy days to help maintain their loft and performance.