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Lost Dog 15º


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Lightweight synthetic-fill big agnes system bag

The Big Agnes Lost Dog Sleeping Bag is part of our system bag line with FireLine™ ECO synthetic insulation offering a roomy, rectangle-shaped sleeping space with an integrated Flex Pad Sleeve on the bottom. With technical fabrics and construction, 100% recycled, super-warm insulation, and tons of comfort features, these comfortable sleeping bags are designed to be lightweight enough for backpacking but cozy enough you'll want them in the campground too. The streamlined silhouette and Flow™ construction increase the thermal efficiency keeping you warm from head to toe. The Flex Pad Sleeve unites easily with your pad, and as you change positions over the course of the night, will keep you from rolling off your pad.


The Big Agnes System bags offer technical, roomy sleeping spaces for those who aren't willing to sacrifice comfort or packability  

Streamlined silhouette for increased thermal efficiency 

Flex Pad Sleeve features stretch construction that accommodates multiple pad widths, and easily connects your bag to your pad  

Regular and Long bags fit 20" - 25" wide pads, Wide Long bags fit 25" - 30" wide pads

Free Range Hood gives you the freedom to lift your head. Jacket-style hood opening contours to the shape of your face for a comfortable, snug fit

Low-profile cordlock lets you un-cinch the hood with one hand

Pillow Barn – keeps your pillow tucked in tight all night

Internal hood drawcord gives you a secure, cozy fit when cinched

Free Range Footbox -  creates wiggle room for your feet

Rectangular shaped bag

Anti-snag zipper for a smooth, quick zip 

Regular: 65" / 165cm YKK #5 anti-snag locking zipper

Long: 70" / 178cm YKK #5 anti-snag locking zipper

Wide Long: 70" / 178cm YKK #5 anti-snag locking zipper

Zipper Garage

Mate together left and right zip bags

No-draft collar, no-draft wedge, no-draft zipper

Interior fabric loops for sleeping bag liners

Exterior loops for hang drying or storage

Mesh storage sack & polyester ripstop stuff sack


Regular Long Wide Long 
Total Weight 3lb 3oz 3lb 10oz 4lb
Fill Type FireLine™ Eco FireLine™ Eco FireLine™ Eco
Total Fill Weight 31 oz 35 oz 40 oz
Compressed Bag Size 8" x 9.5" 8" x 10.5" 9" x 12.5"
Stuff Sack Size 21L 9" x 20" 21L 9" x 20" 26L 10" x 21"
Max User Height 6' 6' 6"
Recommended Pad Size 20" - 25" x 72" 20" - 25" x 78" 25" - 30" x 78"
Shoulder Girth 69" 72"
Hip Girth 60" 63"
Foot Girth 49" 52"


Nylon ripstop shell fabric with a water repellent finish

Soft, cozy polyester lining

FireLine™ ECO Synthetic Insulation - 100% post-consumer recycled polyester. Features low denier fibers that are tightly woven and provide high loft, compressibility, high weight-to-warmth ratio and durability