Petrel 10 UL Sleeping Bag

The Feathered Friends Petrel 10 UL is a premium 10°F (-12.2°C) women’s sleeping bag released for the 2025/2026 season. Though the ideal height for a Medium is 5’9″, it fits a 5’10” hiker perfectly with extra room in the footbox. Featuring 950+ fill power down and an upgraded Pertex® Quantum Pro® shell, it is the ultimate gold standard for cold sleepers.

Feathered Friends Petrel 10 UL Sleeping Bag Review

This is a full field-test and review of the new Feathered Friends Petrel 10 UL, released for the 2025/2026 season. I recently transitioned from the men’s Lark 10 to this women-specific model. Back in 2020, I was worried that at 5’10”, the women’s dimensions wouldn’t be comfortable for a side-sleeper who moves a lot, but this bag is incredibly roomy while providing superior warmth.

The Fit: Perfect for Taller Hikers

Height Versatility: The “ideal” sleeper height for the Medium is 5’9″, but at 5’10”, the fit is actually perfect.
No Restrictions: Even as a side-sleeper who moves a lot, I don’t feel restricted.
Length: My feet don’t push against the end of the footbox, keeping them warm and comfortable.
Interior Space: There is enough internal room to tuck in my electronics and water filter on cold nights.

Warmth & Performance for Cold Sleepers

As a cold sleeper, I’ve found that the Petrel warms up much faster than the Lark because the shoulder opening is smaller and more efficient at trapping heat.

My Sleep System: To stay comfortable, I wear Smartwool Merino 250 Base Layer tops and bottoms, a fleece-lined hat, and Heat Holders socks.
Layering for Extremes: If temps drop toward freezing, I add fleece pajamas. I can even fit my 55°F summer bag inside the Petrel as an extra layer for sub-freezing nights.
Hood & Draft Collar: The 3D contoured hood fits perfectly at 5’10”. Combined with the draft collar and face cinches, it seals in body heat so well that I’d likely be fine even without my fleece hat.
Footbox: The extra fill in the footbox works as advertised; my feet have never been cold in this bag.

Design Updates for 2025/2026

Upgraded Shell: All-new Pertex® Quantum Pro® for better water resistance.
Reinforced Footbox: Features Pertex® Diamond Fuse 15 denier lining for extra abrasion protection.
Anti-Snag Zip Guard: A new strengthening layer along the zipper prevents snags, though it is a bit noisier than previous models.
Colors: I chose the Magenta, but it is also available in Cerulean Blue, Flame orange, and undyed.