Windproof

A wind-resistant down jacket prevents heat loss from air convection. Windproof ratings are often measured in the amount of cubic feet per minute (CFM) or metres squared per second (m²/sec) of about a 30-mile-per-hour wind that can pass through one square measurement of the material. As such, a lower number show that the garment is more effective when it comes to blocking wind. At a wind speed of 30 miles per hour, our fabric is penetrated by 1 cfm of air.