Western Mountaineering Flylite 36Deg

FlyLite – Ultralight Summer Sleeping Bag

The FlyLite is our lightest sleeping bag ever—a purpose-built ultralight summer sleeping bag for thru-hikers, fastpackers, and minimalist adventurers shaving every possible ounce. Weighing just 14.3 ounces, it redefines what’s possible in packable sleep systems for warm weather trips.

This half-zip mummy-style bag is constructed with 10D nylon ExtremeLite™ shell fabric and filled with 850+ fill power goose down for maximum loft and minimal bulk. The FlyLite is rated to 36°F, making it ideal for summer conditions in high alpine zones, desert nights, or anywhere that weight savings are top priority and insulation needs are modest.

The narrow cut and half-length zipper help reduce weight even further, while the insulated draft tube keeps warmth sealed in on cooler evenings. Despite its minimalism, the FlyLite still maintains the Western Mountaineering standard for craftsmanship, durability, and loft retention—even after hundreds of trail nights.

Best used with a hooded layer or insulated jacket on colder nights, the FlyLite isn’t just light—it’s versatile. It compresses to the size of a water bottle and easily fits into the smallest packs, making it a favorite among thru-hikers on routes like the PCT, CT, or JMT.

If you’re the kind of backpacker who trims toothbrushes, cuts pack weight, and watches every gram—this is your bag. When conditions are right, the FlyLite lets you travel farther, faster, and sleep better, all with fewer ounces on your back.

Proudly made in the USA.

Features:

• Filled with 850+ Fill Power ethically-sourced premium goose down
• Continuous baffles allow you to shift down for more insulation in colder weather
• Half-length #3 YKK coil zipper keeps bag ultralight while providing a smooth unzipping experience
• Insulated Draft Tube blocks cold air and keeps the torso better insulated
• Micro-baffled construction eliminates cold spots while making bag extremely packable
• Breathable 10 denier nylon taffeta outer shell makes bag ultralight yet durable
• Comes with ultralight stuff sack and breathable mesh storage bag
• 14 oz. Total Weight