Big Agnes Alpha Direct Fleece Sleeping Bag Liner

This liner from Big Agnes is built from Polartec Alpha Direct fleece, made of 100% recycled polyester, rather than the tighter-woven cotton or silk liners common elsewhere in the category. At 177g (Regular), it is a lightweight add-on rather than a standalone sleeping bag: its job is to extend the usable temperature range of an existing quilt or bag by roughly 3-6°C, per the manufacturer's own figures, or to serve alone as a warm-weather bag substitute. The mummy-shaped liner has a simple drawcord hood for closing around the head, and a reversible zipper that works with both left- and right-zip sleeping bags, so it does not lock you into a specific bag orientation. The inner nylon ripstop and polyester mesh stuff sack keeps the packed liner contained without adding real bulk. It suits thru-hikers who want to fine-tune warmth without carrying a second full bag, or travelers who prefer a washable, packable layer between themselves and a shared or rented sleeping bag. Specs beyond fabric, weight, and shape are not published for this item.