It is purportedly temperature rated to -25 (with moderate activity) and 25 (with light activity).

Warm enough for cooler days and stylish enough for the office or evenings out. These lightweight insulated jackets are the ones you'll want to always have near the door. They're super versatile, weather resistant and breathable, helping you feel great from morning commute to mountain peak.

Overview: LL Bean Ultralight 850 Down Jacket ($199) It's touted to be wearable across a massive, 50-degree temperature range, from 25 degrees down to minus-25 F.

Warm, light and now watertight, our super versatile down jacket keeps you comfortable and dry anytime, in any weather.

As fill power increases, the down can trap more air which, in turn, allows more insulation from the down. For example, one (1) ounce of 800 fill power goose down will loft to 800 cubic inches. So 850 fill power will 'bloom' or 'loft' higher than 800 fill power.

L.L.Bean rates this jacket comfortable to 30° F during light activity and -20° F during moderate activity. The jacket is slightly fitted, but does run big – I'm 5'9″ and 155 and normally wear a size medium but would have gone with a size small as this jacket is meant to insulate and layer well.

It's also more water resistant, with DownTek PFC-Free down that repels more water to protect against cold and clumping.

1. Shell and lining: 100% recycled ripstop nylon.
2. Machine wash and dry.

These feathers trap air close to the body to keep you warm. Down has a highly efficient warmth-to-weight ratio, which results in a lightweight, insulated jacket. In cold weather, your body loses thermal energy to the cold air around you. Trapping air in the lining of your jacket helps to slow down this heat loss.

They are only splashproof. If they are exposed to water for a long time, they will lose their fluffiness. They are made of feathers, after all. If you need to wear your it while it's raining, make sure to wear a raincoat over it.

So 850 fill power will 'bloom' or 'loft' higher than 800 fill power. The higher the fill power the larger the down cluster. Larger down clusters will loft higher; sleep softer, last longer and sleep warmer.

A higher down fill rating doesn't necessarily mean one jacket will be warmer than another. The down fill rating number is a measurement of down quality, meaning the cubic inches of loft one ounce of the specific down produces. A higher rating means less down fill is required to capture the same amount of heat.

ULTRA LIGHT DOWN: Amazingly light, warm, and compact. Packs up easily in an included pouch.