Kelty Cosmic Synthetic Fill 40° Regular Sleeping Bag – Lightweight & Packable

A versatile three-season sleeping bag

Meet the Kelty Cosmic Synthetic Fill 40 Degree bag, designed to balance warmth, weight, and value for backpackers and campers alike. It uses CirroLoft synthetic insulation to deliver reliable warmth without added bulk, while a soft nylon taffeta lining stays gentle against the skin after a long day on the trail. The bag is built to perform in damp or cool nights, with a design that keeps you comfortable without forcing you to trade space for warmth.

Lightweight warmth with thoughtful details

The Cosmic Synthetic is rated for 40°F, with a fill weight of 24 oz and a total trail weight around 2 lb 6 oz. In its non-compressed form, it stuffs to roughly 15 x 8 inches, helping you keep your pack lean for longer treks. Its regular length is designed to fit sleepers up to around 6 ft, while length options cover a range from about 5 ft 8 in to 6 ft 6 in, giving you a comfortable, natural fit for most hikers.

Packable design and handy features

• Integrated compression stuff sack to minimize bulk in your pack
• CirroLoft synthetic insulation provides warmth with consistent loft, even in damp environments
• Natural, roomy footbox supports toe movement for added comfort
• Exterior stash pocket holds small overnight essentials within easy reach

Durability, fit, and real-world use

Kelty’s craftsmanship shines through in the Cosmic Synthetic bag, built to endure the rough-and-tumble of trail life from the campground to backcountry treks. The colorway—Duffel Bag Green/Smoke—offers a subdued outdoor look that pairs well with most packs. While warmth, weight, and packability are impressive on paper, the real value comes from its everyday versatility: quick setup in camp, reliable warmth on crisp spring nights, and compact packing for carriers that value every ounce. If you’re shopping for a three-season bag that balances warmth with a minimal footprint, the Cosmic Synthetic provides a practical option to consider.

What you get and how to use

In addition to a 40°F rated bag, you’ll gain a reliable partner for damp nights, simple packing, and straightforward care. Think about autumnal campouts, shoulder-season trips, or safer options for spring sleep comfort. The combination of CirroLoft insulation, a soft interior, and a smartly designed footbox aims to deliver consistent comfort without heavy reliance on extra gear.