If you've ever wished for a less-constrictive sleeping bag that keeps you comfortable in a variety of cool-to-warm conditions, the Trek may become your go-to bag. The Free-Flow Zip system allows you to open the bag sequentially for ventilation up to the point where it is opened flat as a quilt - you can even secure the snaps around your shoulders, open the footbox zipper and 'wear' the Trek around camp. 650 fillpower duck down with a non-PFC Ultra-Dry Down treatment keep you insulated in damper conditions. Slip an Aeros Pillow into the hood and enjoy a great night's sleep - wherever your travels take you.